Yu Zhao <yuzhao@xxxxxxxxxx> 于2023年12月26日周二 06:01写道： > > On Mon, Dec 25, 2023 at 2:52 PM Yu Zhao <yuzhao@xxxxxxxxxx> wrote: > > > > On Mon, Dec 25, 2023 at 5:03 AM Kairui Song <ryncsn@xxxxxxxxx> wrote: > > > > > > Yu Zhao <yuzhao@xxxxxxxxxx> 于2023年12月25日周一 14:30写道： > > > > > > > > On Wed, Dec 20, 2023 at 1:24 AM Kairui Song <ryncsn@xxxxxxxxx> wrote: > > > > > > > > > > Yu Zhao <yuzhao@xxxxxxxxxx> 于2023年12月20日周三 16:17写道： > > > > > > > > > > > > On Tue, Dec 19, 2023 at 11:38 PM Yu Zhao <yuzhao@xxxxxxxxxx> wrote: > > > > > > > > > > > > > > On Tue, Dec 19, 2023 at 11:58 AM Kairui Song <ryncsn@xxxxxxxxx> wrote: > > > > > > > > > > > > > > > > Yu Zhao <yuzhao@xxxxxxxxxx> 于2023年12月19日周二 11:45写道： > > > > > > > > > > > > > > > > > > On Mon, Dec 18, 2023 at 8:21 PM Yu Zhao <yuzhao@xxxxxxxxxx> wrote: > > > > > > > > > > > > > > > > > > > > On Mon, Dec 18, 2023 at 11:05 AM Kairui Song <ryncsn@xxxxxxxxx> wrote: > > > > > > > > > > > > > > > > > > > > > > Yu Zhao <yuzhao@xxxxxxxxxx> 于2023年12月15日周五 12:56写道： > > > > > > > > > > > > > > > > > > > > > > > > On Thu, Dec 14, 2023 at 04:51:00PM -0700, Yu Zhao wrote: > > > > > > > > > > > > > On Thu, Dec 14, 2023 at 11:38 AM Kairui Song <ryncsn@xxxxxxxxx> wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > > Yu Zhao <yuzhao@xxxxxxxxxx> 于2023年12月14日周四 11:09写道： > > > > > > > > > > > > > > > On Wed, Dec 13, 2023 at 12:59:14AM -0700, Yu Zhao wrote: > > > > > > > > > > > > > > > > On Tue, Dec 12, 2023 at 8:03 PM Kairui Song <ryncsn@xxxxxxxxx> wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Kairui Song <ryncsn@xxxxxxxxx> 于2023年12月12日周二 14:52写道： > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Yu Zhao <yuzhao@xxxxxxxxxx> 于2023年12月12日周二 06:07写道： > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > On Fri, Dec 8, 2023 at 1:24 AM Kairui Song <ryncsn@xxxxxxxxx> wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Yu Zhao <yuzhao@xxxxxxxxxx> 于2023年12月8日周五 14:14写道： > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Unmapped folios accessed through file descriptors can be > > > > > > > > > > > > > > > > > > > > > underprotected. Those folios are added to the oldest generation based > > > > > > > > > > > > > > > > > > > > > on: > > > > > > > > > > > > > > > > > > > > > 1. The fact that they are less costly to reclaim (no need to walk the > > > > > > > > > > > > > > > > > > > > > rmap and flush the TLB) and have less impact on performance (don't > > > > > > > > > > > > > > > > > > > > > cause major PFs and can be non-blocking if needed again). > > > > > > > > > > > > > > > > > > > > > 2. The observation that they are likely to be single-use. E.g., for > > > > > > > > > > > > > > > > > > > > > client use cases like Android, its apps parse configuration files > > > > > > > > > > > > > > > > > > > > > and store the data in heap (anon); for server use cases like MySQL, > > > > > > > > > > > > > > > > > > > > > it reads from InnoDB files and holds the cached data for tables in > > > > > > > > > > > > > > > > > > > > > buffer pools (anon). > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > However, the oldest generation can be very short lived, and if so, it > > > > > > > > > > > > > > > > > > > > > doesn't provide the PID controller with enough time to respond to a > > > > > > > > > > > > > > > > > > > > > surge of refaults. (Note that the PID controller uses weighted > > > > > > > > > > > > > > > > > > > > > refaults and those from evicted generations only take a half of the > > > > > > > > > > > > > > > > > > > > > whole weight.) In other words, for a short lived generation, the > > > > > > > > > > > > > > > > > > > > > moving average smooths out the spike quickly. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > To fix the problem: > > > > > > > > > > > > > > > > > > > > > 1. For folios that are already on LRU, if they can be beyond the > > > > > > > > > > > > > > > > > > > > > tracking range of tiers, i.e., five accesses through file > > > > > > > > > > > > > > > > > > > > > descriptors, move them to the second oldest generation to give them > > > > > > > > > > > > > > > > > > > > > more time to age. (Note that tiers are used by the PID controller > > > > > > > > > > > > > > > > > > > > > to statistically determine whether folios accessed multiple times > > > > > > > > > > > > > > > > > > > > > through file descriptors are worth protecting.) > > > > > > > > > > > > > > > > > > > > > 2. When adding unmapped folios to LRU, adjust the placement of them so > > > > > > > > > > > > > > > > > > > > > that they are not too close to the tail. The effect of this is > > > > > > > > > > > > > > > > > > > > > similar to the above. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > On Android, launching 55 apps sequentially: > > > > > > > > > > > > > > > > > > > > > Before After Change > > > > > > > > > > > > > > > > > > > > > workingset_refault_anon 25641024 25598972 0% > > > > > > > > > > > > > > > > > > > > > workingset_refault_file 115016834 106178438 -8% > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Hi Yu, > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks you for your amazing works on MGLRU. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I believe this is the similar issue I was trying to resolve previously: > > > > > > > > > > > > > > > > > > > > https://lwn.net/Articles/945266/ > > > > > > > > > > > > > > > > > > > > The idea is to use refault distance to decide if the page should be > > > > > > > > > > > > > > > > > > > > place in oldest generation or some other gen, which per my test, > > > > > > > > > > > > > > > > > > > > worked very well, and we have been using refault distance for MGLRU in > > > > > > > > > > > > > > > > > > > > multiple workloads. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > There are a few issues left in my previous RFC series, like anon pages > > > > > > > > > > > > > > > > > > > > in MGLRU shouldn't be considered, I wanted to collect feedback or test > > > > > > > > > > > > > > > > > > > > cases, but unfortunately it seems didn't get too much attention > > > > > > > > > > > > > > > > > > > > upstream. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I think both this patch and my previous series are for solving the > > > > > > > > > > > > > > > > > > > > file pages underpertected issue, and I did a quick test using this > > > > > > > > > > > > > > > > > > > > series, for mongodb test, refault distance seems still a better > > > > > > > > > > > > > > > > > > > > solution (I'm not saying these two optimization are mutually exclusive > > > > > > > > > > > > > > > > > > > > though, just they do have some conflicts in implementation and solving > > > > > > > > > > > > > > > > > > > > similar problem): > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Previous result: > > > > > > > > > > > > > > > > > > > > ================================================================== > > > > > > > > > > > > > > > > > > > > Execution Results after 905 seconds > > > > > > > > > > > > > > > > > > > > ------------------------------------------------------------------ > > > > > > > > > > > > > > > > > > > > Executed Time (µs) Rate > > > > > > > > > > > > > > > > > > > > STOCK_LEVEL 2542 27121571486.2 0.09 txn/s > > > > > > > > > > > > > > > > > > > > ------------------------------------------------------------------ > > > > > > > > > > > > > > > > > > > > TOTAL 2542 27121571486.2 0.09 txn/s > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > This patch: > > > > > > > > > > > > > > > > > > > > ================================================================== > > > > > > > > > > > > > > > > > > > > Execution Results after 900 seconds > > > > > > > > > > > > > > > > > > > > ------------------------------------------------------------------ > > > > > > > > > > > > > > > > > > > > Executed Time (µs) Rate > > > > > > > > > > > > > > > > > > > > STOCK_LEVEL 1594 27061522574.4 0.06 txn/s > > > > > > > > > > > > > > > > > > > > ------------------------------------------------------------------ > > > > > > > > > > > > > > > > > > > > TOTAL 1594 27061522574.4 0.06 txn/s > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Unpatched version is always around ~500. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks for the test results! > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I think there are a few points here: > > > > > > > > > > > > > > > > > > > > - Refault distance make use of page shadow so it can better > > > > > > > > > > > > > > > > > > > > distinguish evicted pages of different access pattern (re-access > > > > > > > > > > > > > > > > > > > > distance). > > > > > > > > > > > > > > > > > > > > - Throttled refault distance can help hold part of workingset when > > > > > > > > > > > > > > > > > > > > memory is too small to hold the whole workingset. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > So maybe part of this patch and the bits of previous series can be > > > > > > > > > > > > > > > > > > > > combined to work better on this issue, how do you think? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I'll try to find some time this week to look at your RFC. It'd be a > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Hi Yu, > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I'm working on V4 of the RFC now, which just update some comments, and > > > > > > > > > > > > > > > > > skip anon page re-activation in refault path for mglru which was not > > > > > > > > > > > > > > > > > very helpful, only some tiny adjustment. > > > > > > > > > > > > > > > > > And I found it easier to test with fio, using following test script: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > #!/bin/bash > > > > > > > > > > > > > > > > > swapoff -a > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > modprobe brd rd_nr=1 rd_size=16777216 > > > > > > > > > > > > > > > > > mkfs.ext4 /dev/ram0 > > > > > > > > > > > > > > > > > mount /dev/ram0 /mnt > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > mkdir -p /sys/fs/cgroup/benchmark > > > > > > > > > > > > > > > > > cd /sys/fs/cgroup/benchmark > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > echo 4G > memory.max > > > > > > > > > > > > > > > > > echo $$ > cgroup.procs > > > > > > > > > > > > > > > > > echo 3 > /proc/sys/vm/drop_caches > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > fio -name=mglru --numjobs=12 --directory=/mnt --size=1024m \ > > > > > > > > > > > > > > > > > --buffered=1 --ioengine=io_uring --iodepth=128 \ > > > > > > > > > > > > > > > > > --iodepth_batch_submit=32 --iodepth_batch_complete=32 \ > > > > > > > > > > > > > > > > > --rw=randread --random_distribution=zipf:0.5 --norandommap \ > > > > > > > > > > > > > > > > > --time_based --ramp_time=5m --runtime=5m --group_reporting > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > zipf:0.5 is used here to simulate a cached read with slight bias > > > > > > > > > > > > > > > > > towards certain pages. > > > > > > > > > > > > > > > > > Unpatched 6.7-rc4: > > > > > > > > > > > > > > > > > Run status group 0 (all jobs): > > > > > > > > > > > > > > > > > READ: bw=6548MiB/s (6866MB/s), 6548MiB/s-6548MiB/s > > > > > > > > > > > > > > > > > (6866MB/s-6866MB/s), io=1918GiB (2060GB), run=300001-300001msec > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Patched with RFC v4: > > > > > > > > > > > > > > > > > Run status group 0 (all jobs): > > > > > > > > > > > > > > > > > READ: bw=7270MiB/s (7623MB/s), 7270MiB/s-7270MiB/s > > > > > > > > > > > > > > > > > (7623MB/s-7623MB/s), io=2130GiB (2287GB), run=300001-300001msec > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Patched with this series: > > > > > > > > > > > > > > > > > Run status group 0 (all jobs): > > > > > > > > > > > > > > > > > READ: bw=7098MiB/s (7442MB/s), 7098MiB/s-7098MiB/s > > > > > > > > > > > > > > > > > (7442MB/s-7442MB/s), io=2079GiB (2233GB), run=300002-300002msec > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > MGLRU off: > > > > > > > > > > > > > > > > > Run status group 0 (all jobs): > > > > > > > > > > > > > > > > > READ: bw=6525MiB/s (6842MB/s), 6525MiB/s-6525MiB/s > > > > > > > > > > > > > > > > > (6842MB/s-6842MB/s), io=1912GiB (2052GB), run=300002-300002msec > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > - If I change zipf:0.5 to random: > > > > > > > > > > > > > > > > > Unpatched 6.7-rc4: > > > > > > > > > > > > > > > > > Patched with this series: > > > > > > > > > > > > > > > > > Run status group 0 (all jobs): > > > > > > > > > > > > > > > > > READ: bw=5975MiB/s (6265MB/s), 5975MiB/s-5975MiB/s > > > > > > > > > > > > > > > > > (6265MB/s-6265MB/s), io=1750GiB (1879GB), run=300002-300002msec > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Patched with RFC v4: > > > > > > > > > > > > > > > > > Run status group 0 (all jobs): > > > > > > > > > > > > > > > > > READ: bw=5987MiB/s (6278MB/s), 5987MiB/s-5987MiB/s > > > > > > > > > > > > > > > > > (6278MB/s-6278MB/s), io=1754GiB (1883GB), run=300001-300001msec > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Patched with this series: > > > > > > > > > > > > > > > > > Run status group 0 (all jobs): > > > > > > > > > > > > > > > > > READ: bw=5839MiB/s (6123MB/s), 5839MiB/s-5839MiB/s > > > > > > > > > > > > > > > > > (6123MB/s-6123MB/s), io=1711GiB (1837GB), run=300001-300001msec > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > MGLRU off: > > > > > > > > > > > > > > > > > Run status group 0 (all jobs): > > > > > > > > > > > > > > > > > READ: bw=5689MiB/s (5965MB/s), 5689MiB/s-5689MiB/s > > > > > > > > > > > > > > > > > (5965MB/s-5965MB/s), io=1667GiB (1790GB), run=300003-300003msec > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > fio uses ramdisk so LRU accuracy will have smaller impact. The Mongodb > > > > > > > > > > > > > > > > > test I provided before uses a SATA SSD so it will have a much higher > > > > > > > > > > > > > > > > > impact. I'll provides a script to setup the test case and run it, it's > > > > > > > > > > > > > > > > > more complex to setup than fio since involving setting up multiple > > > > > > > > > > > > > > > > > replicas and auth and hundreds of GB of test fixtures, I'm currently > > > > > > > > > > > > > > > > > occupied by some other tasks but will try best to send them out as > > > > > > > > > > > > > > > > > soon as possible. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks! Apparently your RFC did show better IOPS with both access > > > > > > > > > > > > > > > > patterns, which was a surprise to me because it had higher refaults > > > > > > > > > > > > > > > > and usually higher refautls result in worse performance. > > > > > > > > > > > > > > > > > > > > > > > > And thanks for providing the refaults I requested for -- your data > > > > > > > > > > > > below confirms what I mentioned above: > > > > > > > > > > > > > > > > > > > > > > > > For fio: > > > > > > > > > > > > Your RFC This series Change > > > > > > > > > > > > workingset_refault_file 628192729 596790506 -5% > > > > > > > > > > > > IOPS 1862k 1830k -2% > > > > > > > > > > > > > > > > > > > > > > > > For MongoDB: > > > > > > > > > > > > Your RFC This series Change > > > > > > > > > > > > workingset_refault_anon 10512 35277 +30% > > > > > > > > > > > > workingset_refault_file 22751782 20335355 -11% > > > > > > > > > > > > total 22762294 20370632 -11% > > > > > > > > > > > > TPS 0.09 0.06 -33% > > > > > > > > > > > > > > > > > > > > > > > > For MongoDB, this series should be a big win (but apparently it's not), > > > > > > > > > > > > especially when using zram, since an anon refault should be a lot > > > > > > > > > > > > cheaper than a file refault. > > > > > > > > > > > > > > > > > > > > > > > > So, I'm baffled... > > > > > > > > > > > > > > > > > > > > > > > > One important detail I forgot to mention: based on your data from > > > > > > > > > > > > lru_gen_full, I think there is another difference between our Kconfigs: > > > > > > > > > > > > > > > > > > > > > > > > Your Kconfig My Kconfig Max possible > > > > > > > > > > > > LRU_REFS_WIDTH 1 2 2 > > > > > > > > > > > > > > > > > > > > > > Hi Yu, > > > > > > > > > > > > > > > > > > > > > > Thanks for the info, my fault, I forgot to update my config as I was > > > > > > > > > > > testing some other features. > > > > > > > > > > > Buf after I changed LRU_REFS_WIDTH to 2 by disabling IDLE_PAGE, thing > > > > > > > > > > > got much worse for MongoDB test: > > > > > > > > > > > > > > > > > > > > > > With LRU_REFS_WIDTH == 2: > > > > > > > > > > > > > > > > > > > > > > This patch: > > > > > > > > > > > ================================================================== > > > > > > > > > > > Execution Results after 919 seconds > > > > > > > > > > > ------------------------------------------------------------------ > > > > > > > > > > > Executed Time (µs) Rate > > > > > > > > > > > STOCK_LEVEL 488 27598136201.9 0.02 txn/s > > > > > > > > > > > ------------------------------------------------------------------ > > > > > > > > > > > TOTAL 488 27598136201.9 0.02 txn/s > > > > > > > > > > > > > > > > > > > > > > memcg 86 /system.slice/docker-1c3a90be9f0a072f5719332419550cd0e1455f2cd5863bc2780ca4d3f913ece5.scope > > > > > > > > > > > node 0 > > > > > > > > > > > 1 948187 0x 0x > > > > > > > > > > > 0 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 1 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 2 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 3 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 2 948187 0 6051788· > > > > > > > > > > > 0 0r 0e 0p 11916r > > > > > > > > > > > 66442e 0p > > > > > > > > > > > 1 0r 0e 0p 903r > > > > > > > > > > > 16888e 0p > > > > > > > > > > > 2 0r 0e 0p 459r > > > > > > > > > > > 9764e 0p > > > > > > > > > > > 3 0r 0e 0p 0r > > > > > > > > > > > 0e 2874p > > > > > > > > > > > 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 3 948187 1353160 6351· > > > > > > > > > > > 0 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 1 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 2 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 3 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 4 73045 23573 12· > > > > > > > > > > > 0 0R 0T 0 3498607R > > > > > > > > > > > 4868605T 0· > > > > > > > > > > > 1 0R 0T 0 3012246R > > > > > > > > > > > 3270261T 0· > > > > > > > > > > > 2 0R 0T 0 2498608R > > > > > > > > > > > 2839104T 0· > > > > > > > > > > > 3 0R 0T 0 0R > > > > > > > > > > > 1983947T 0· > > > > > > > > > > > 1486579L 0O 1380614Y 2945N > > > > > > > > > > > 2945F 2734A > > > > > > > > > > > > > > > > > > > > > > workingset_refault_anon 0 > > > > > > > > > > > workingset_refault_file 18130598 > > > > > > > > > > > > > > > > > > > > > > total used free shared buff/cache available > > > > > > > > > > > Mem: 31978 6705 312 20 24960 24786 > > > > > > > > > > > Swap: 31977 4 31973 > > > > > > > > > > > > > > > > > > > > > > RFC: > > > > > > > > > > > ================================================================== > > > > > > > > > > > Execution Results after 908 seconds > > > > > > > > > > > ------------------------------------------------------------------ > > > > > > > > > > > Executed Time (µs) Rate > > > > > > > > > > > STOCK_LEVEL 2252 27159962888.2 0.08 txn/s > > > > > > > > > > > ------------------------------------------------------------------ > > > > > > > > > > > TOTAL 2252 27159962888.2 0.08 txn/s > > > > > > > > > > > > > > > > > > > > > > workingset_refault_anon 22585 > > > > > > > > > > > workingset_refault_file 22715256 > > > > > > > > > > > > > > > > > > > > > > memcg 66 /system.slice/docker-0989446ff78106e32d3f400a0cf371c9a703281bded86d6d6bb1af706ebb25da.scope > > > > > > > > > > > node 0 > > > > > > > > > > > 22 563007 2274 1198225· > > > > > > > > > > > 0 0r 1e 0p 0r > > > > > > > > > > > 697076e 0p > > > > > > > > > > > 1 0r 0e 0p 0r > > > > > > > > > > > 0e 325661p > > > > > > > > > > > 2 0r 0e 0p 0r > > > > > > > > > > > 0e 888728p > > > > > > > > > > > 3 0r 0e 0p 0r > > > > > > > > > > > 0e 3602238p > > > > > > > > > > > 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 23 532222 7525 4948747· > > > > > > > > > > > 0 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 1 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 2 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 3 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 24 500367 1214667 3292· > > > > > > > > > > > 0 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 1 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 2 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 3 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 0 0 0 0 > > > > > > > > > > > 0 0· > > > > > > > > > > > 25 469692 40797 466· > > > > > > > > > > > 0 0R 271T 0 0R > > > > > > > > > > > 1162165T 0· > > > > > > > > > > > 1 0R 0T 0 774028R > > > > > > > > > > > 1205332T 0· > > > > > > > > > > > 2 0R 0T 0 0R > > > > > > > > > > > 932484T 0· > > > > > > > > > > > 3 0R 1T 0 0R > > > > > > > > > > > 4252158T 0· > > > > > > > > > > > 25178380L 156515O 23953602Y 59234N > > > > > > > > > > > 49391F 48664A > > > > > > > > > > > > > > > > > > > > > > total used free shared buff/cache available > > > > > > > > > > > Mem: 31978 6968 338 5 24671 24555 > > > > > > > > > > > Swap: 31977 1533 30444 > > > > > > > > > > > > > > > > > > > > > > Using same mongodb config (a 3 replica cluster using the same config): > > > > > > > > > > > { > > > > > > > > > > > "net": { > > > > > > > > > > > "bindIpAll": true, > > > > > > > > > > > "ipv6": false, > > > > > > > > > > > "maxIncomingConnections": 10000, > > > > > > > > > > > }, > > > > > > > > > > > "setParameter": { > > > > > > > > > > > "disabledSecureAllocatorDomains": "*" > > > > > > > > > > > }, > > > > > > > > > > > "replication": { > > > > > > > > > > > "oplogSizeMB": 10480, > > > > > > > > > > > "replSetName": "issa-tpcc_0" > > > > > > > > > > > }, > > > > > > > > > > > "security": { > > > > > > > > > > > "keyFile": "/data/db/keyfile" > > > > > > > > > > > }, > > > > > > > > > > > "storage": { > > > > > > > > > > > "dbPath": "/data/db/", > > > > > > > > > > > "syncPeriodSecs": 60, > > > > > > > > > > > "directoryPerDB": true, > > > > > > > > > > > "wiredTiger": { > > > > > > > > > > > "engineConfig": { > > > > > > > > > > > "cacheSizeGB": 5 > > > > > > > > > > > } > > > > > > > > > > > } > > > > > > > > > > > }, > > > > > > > > > > > "systemLog": { > > > > > > > > > > > "destination": "file", > > > > > > > > > > > "logAppend": true, > > > > > > > > > > > "logRotate": "rename", > > > > > > > > > > > "path": "/data/db/mongod.log", > > > > > > > > > > > "verbosity": 0 > > > > > > > > > > > } > > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > > > The test environment have 32g memory and 16 core. > > > > > > > > > > > > > > > > > > > > > > Per my analyze, the access pattern for the mongodb test is that page > > > > > > > > > > > will be re-access long after it's evicted so PID controller won't > > > > > > > > > > > protect higher tier. That RFC will make use of the long existing > > > > > > > > > > > shadow to do feedback to PID/Gen so the result will be much better. > > > > > > > > > > > Still need more adjusting though, will try to do a rebase on top of > > > > > > > > > > > mm-unstable which includes your patch. > > > > > > > > > > > > > > > > > > > > > > I've no idea why the workingset_refault_* is higher in the better > > > > > > > > > > > case, this a clearly an IO bound workload, Memory and IO is busy while > > > > > > > > > > > CPU is not full... > > > > > > > > > > > > > > > > > > > > > > I've uploaded my local reproducer here: > > > > > > > > > > > https://github.com/ryncsn/emm-test-project/tree/master/mongo-cluster > > > > > > > > > > > https://github.com/ryncsn/py-tpcc > > > > > > > > > > > > > > > > > > > > Thanks for the repos -- I'm trying them right now. Which MongoDB > > > > > > > > > > version did you use? setup.sh didn't seem to install it. > > > > > > > > > > > > > > > > > > > > Also do you have a QEMU image? It'd be a lot easier for me to > > > > > > > > > > duplicate the exact environment by looking into it. > > > > > > > > > > > > > > > > > > I ended up using docker.io/mongodb/mongodb-community-server:latest, > > > > > > > > > and it's not working: > > > > > > > > > > > > > > > > > > # docker exec -it mongo-r1 mongosh --eval \ > > > > > > > > > '"rs.initiate({ > > > > > > > > > _id: "issa-tpcc_0", > > > > > > > > > members: [ > > > > > > > > > {_id: 0, host: "mongo-r1"}, > > > > > > > > > {_id: 1, host: "mongo-r2"}, > > > > > > > > > {_id: 2, host: "mongo-r3"} > > > > > > > > > ] > > > > > > > > > })"' > > > > > > > > > Emulate Docker CLI using podman. Create /etc/containers/nodocker to quiet msg. > > > > > > > > > Error: can only create exec sessions on running containers: container > > > > > > > > > state improper > > > > > > > > > > > > > > > > Hi Yu, > > > > > > > > > > > > > > > > I've updated the test repo: > > > > > > > > https://github.com/ryncsn/emm-test-project/tree/master/mongo-cluster > > > > > > > > > > > > > > > > I've tested it on top of latest Fedora Cloud Image 39 and it worked > > > > > > > > well for me, the README now contains detailed and not hard to follow > > > > > > > > steps to reproduce this test. > > > > > > > > > > > > > > Thanks. I was following the instructions down to the letter and it > > > > > > > fell apart again at line 46 (./tpcc.py). > > > > > > > > > > > > I think you just broke it by > > > > > > https://github.com/ryncsn/py-tpcc/commit/7b9b380d636cb84faa5b11b5562e531f924eeb7e > > > > > > > > > > > > (But it's also possible you actually wanted me to use this latest > > > > > > commit but forgot to account for it in your instructions.) > > > > > > > > > > > > > Were you able to successfully run the benchmark on a fresh VM by > > > > > > > following the instructions? If not, I'd appreciate it if you could do > > > > > > > so and document all the missing steps. > > > > > > > > > > Ah, you are right, I attempted to convert it to Python3 but found it > > > > > only brought more trouble, so I gave up and the instruction is still > > > > > using Python2. However I accidentally pushed the WIP python3 convert > > > > > commit... I've reset the repo to > > > > > https://github.com/ryncsn/py-tpcc/commit/86e862c5cf3b2d1f51e0297742fa837c7a99ebf8, > > > > > this is working well. Sorry for the inconvenient. > > > > > > > > Thanks -- I was able to reproduce results similar to yours. > > > > > > > > > > Hi Yu, > > > > > > Thanks for the testing, and merry xmas. > > > > > > > It turned out the mystery (fewer refaults but worse performance) was caused by > > > > 13.89% 13.89% kswapd0 [kernel.vmlinux] [k] > > > > __list_del_entry_valid_or_report > > > > > > I'm not sure about this, if the task is CPU bounded, this could > > > explain. But it's not, the performance gap is larger when tested on > > > slow IO device. > > > > > > The iostat output during my test run: > > > avg-cpu: %user %nice %system %iowait %steal %idle > > > 7.40 0.00 2.42 83.37 0.00 6.80 > > > Device r/s w/s rkB/s wkB/s rrqm/s wrqm/s > > > %rrqm %wrqm r_await w_await aqu-sz rareq-sz wareq-sz svctm %util > > > vda 35.00 0.80 167.60 17.20 6.90 3.50 > > > 16.47 81.40 0.47 1.62 0.02 4.79 21.50 0.63 2.27 > > > vdb 5999.30 4.80 104433.60 84.00 0.00 8.30 > > > 0.00 63.36 6.54 1.31 39.25 17.41 17.50 0.17 100.00 > > > zram0 0.00 0.00 0.00 0.00 0.00 0.00 > > > 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 > > > > I ran the benchmark on the slowest bare metal I have that roughly > > matches your CPU/DRAM configurations (ThinkPad P1 G4 > > https://support.lenovo.com/us/en/solutions/pd031426). > > > > But it seems you used a VM (vda/vdb) -- I never run performance > > benchmarks in VMs because the host and hypervisor can complicate > > things, for example, in this case, is it possible the host page cache > > cached your disk image containing the database files? > > > > > You can see CPU is waiting for IO, %user is always around 10%. > > > The hotspot you posted only take up 13.89% of the runtime, which > > > shouldn't cause so much performance drop. > > > > > > > > > > > Apparently Fedora has CONFIG_DEBUG_LIST=y by default, and after I > > > > turned it off (the only change I made), this series showed better TPS > > > > (I used"--duration=10800" for more reliable results): > > > > v6.7-rc6 RFC [1] change > > > > total txns 25024 24672 +1% > > > > workingset_refault_anon 573668 680248 -16% > > > > workingset_refault_file 260631976 265808452 -2% > > > > > > I have disabled CONFIG_DEBUG_LIST when doing performance comparison test. > > Also I'd suggest we both use the same distro you shared with me and > the default .config except CONFIG_DEBUG_LIST=n, and v6.7-rc6 for now. > > (I'm attaching the default .config based on /boot/config-6.5.6-300.fc39.x86_64.) > Hi Yu I've been adapting and testing the refault distance series based on latest 6.7. Also I found a serious bug in my previous V3, so I updated it here with some importance changes (using a seperate refault distance model, instead of glueing to active/inactive model): https://github.com/ryncsn/linux/commits/kasong/devel/refault-distance-2024-1/ So far I can conclude that previous result is not caused by host cache, I setup a baremetal test environment, strictly using your config, I gathered some data (I also updated the refault distance patch series, updated version in link above, and also the baremetal hava a fast NVME so the performance gap wasn't so large but still stably observable): With latest 6.7 (Your config): ================================================================== Execution Results after 905 seconds ------------------------------------------------------------------ Executed Time (µs) Rate STOCK_LEVEL 4025 27162035181.5 0.15 txn/s ------------------------------------------------------------------ TOTAL 4025 27162035181.5 0.15 txn/s vmstat: workingset_nodes 82996 workingset_refault_anon 269371 workingset_refault_file 37671044 workingset_activate_anon 121061 workingset_activate_file 8927227 workingset_restore_anon 121061 workingset_restore_file 2578269 workingset_nodereclaim 62394 lru_gen_full: memcg 67 /machine.slice/libpod-38b33777db34724cf8edfbef1ac2e4fd0621f14151e241bbf1430d397d3dee51.scope/container node 0 34 60565 21248 1254331 0 0r 0e 0p 121186r 169948e 0p 1 0r 0e 0p 156224r 222553e 0p 2 0r 0e 0p 0r 0e 4227858p 3 0r 0e 0p 0r 0e 0p 0 0 0 0 0 0 35 41132 714504 4300280 0 0 0 0 0 0 0 1 0 0 0 0 0 0 2 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 36 20586 473476 2105 0 0 0 0 0 0 0 1 0 0 0 0 0 0 2 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 37 2035 817 876 0 6647R 9116T 0 166836R 871850T 0 1 0R 0T 0 110807R 296447T 0 2 0R 268T 0 0R 4655276T 0 3 0R 0T 0 0R 0T 0 12510062L 639646O 11048666Y 45512N 24520F 23613A iostat: avg-cpu: %user %nice %system %iowait %steal %idle 76.29 0.00 12.09 3.50 1.44 6.69 Device tps kB_read/s kB_wrtn/s kB_dscd/s kB_read kB_wrtn kB_dscd dm-0 16.12 684.50 36.93 0.00 649996 35070 0 dm-1 0.05 1.10 0.00 0.00 1044 0 0 nvme0n1 16.47 700.22 39.09 0.00 664922 37118 0 nvme1n1 4905.93 205287.92 1030.70 0.00 194939353 978740 0 zram0 4440.17 5356.90 12404.81 0.00 5086856 11779480 0 free -m: total used free shared buff/cache available Mem: 31830 9475 403 0 21951 21918 Swap: 31829 6500 25329 With latest refault distance series (Your config): ================================================================== Execution Results after 902 seconds ------------------------------------------------------------------ Executed Time (µs) Rate STOCK_LEVEL 4260 27065448172.8 0.16 txn/s ------------------------------------------------------------------ TOTAL 4260 27065448172.8 0.16 txn/s workingset_nodes 113824 workingset_refault_anon 293426 workingset_refault_file 42700484 workingset_activate_anon 0 workingset_activate_file 13410174 workingset_restore_anon 289106 workingset_restore_file 5592042 workingset_nodereclaim 33249 memcg 67 /machine.slice/libpod-8eff6b7b65e34fe0497ff5c0c88c750f6896c43a06bb26e8cd6470de596be76e.scope/container node 0 15 261222 266350 65081 0 0r 0e 0p 185212r 2314329e 0p 1 0r 0e 0p 40887r 710312e 0p 2 0r 0e 0p 0r 0e 5026031p 3 0r 0e 0p 0r 0e 0p 0 0 0 0 0 0 16 199341 267661 5034442 0 0 0 0 0 0 0 1 0 0 0 0 0 0 2 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 17 120655 547852 592 0 0 0 0 0 0 0 1 0 0 0 0 0 0 2 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 18 55172 127769 3855 0 1910R 2975T 0 1894614R 4375361T 0 1 0R 0T 0 2099208R 2861460T 0 2 0R 27T 0 446000R 5569781T 0 3 0R 0T 0 0R 0T 0 2817512L 35421O 2579377Y 10452N 5517F 5414A avg-cpu: %user %nice %system %iowait %steal %idle 76.34 0.00 11.25 4.22 1.29 6.90 Device tps kB_read/s kB_wrtn/s kB_dscd/s kB_read kB_wrtn kB_dscd dm-0 12.85 563.18 30.75 0.00 532390 29070 0 dm-1 0.05 1.10 0.00 0.00 1044 0 0 nvme0n1 13.22 578.97 32.92 0.00 547315 31119 0 nvme1n1 5384.11 229164.12 1038.95 0.00 216635713 982152 0 zram0 3590.88 4730.84 9633.71 0.00 4472204 9107032 0 total used free shared buff/cache available Mem: 31830 10854 520 0 20455 20541 Swap: 31829 4508 27321 You see actually refault distance is now protecting more anon page, total IO on ZRAM is lower, It's mostly CPU bound, and NVME is fast enough, and result in a better performance. Things get more interesting if I disable page idle flag (so refs bits is extended, in your config, refs bit is only one bit, so it maybe overprotect file pages): Latest 6.7 (You config with page idle flag disabled): ================================================================== Execution Results after 904 seconds ------------------------------------------------------------------ Executed Time (µs) Rate STOCK_LEVEL 4016 27122163703.9 0.15 txn/s ------------------------------------------------------------------ TOTAL 4016 27122163703.9 0.15 txn/s workingset_nodes 99637 workingset_refault_anon 309548 workingset_refault_file 45896663 workingset_activate_anon 129401 workingset_activate_file 18461236 workingset_restore_anon 129400 workingset_restore_file 4963707 workingset_nodereclaim 43970 memcg 67 /machine.slice/libpod-7546463bd2b257a9b799817ca11bee1389d7deec20032529098520a89a207d7e.scope/container node 0 27 103004 328070 269733 0 0r 0e 0p 509949r 1957117e 0p 1 0r 0e 0p 141642r 319695e 0p 2 0r 0e 0p 777835r 793518e 0p 3 0r 0e 0p 0r 0e 4333835p 0 0 0 0 0 0 28 82361 24748 5192182 0 0 0 0 0 0 0 1 0 0 0 0 0 0 2 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 29 57025 786386 5681 0 0 0 0 0 0 0 1 0 0 0 0 0 0 2 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 30 18619 76289 1273 0 4295R 8888T 0 222326R 1044601T 0 1 0R 0T 0 117646R 301735T 0 2 0R 0T 0 433431R 825516T 0 3 0R 1T 0 0R 4076839T 0 13369819L 603360O 11981074Y 47388N 26235F 25276A avg-cpu: %user %nice %system %iowait %steal %idle 74.90 0.00 11.96 4.92 1.62 6.60 Device tps kB_read/s kB_wrtn/s kB_dscd/s kB_read kB_wrtn kB_dscd dm-0 14.93 645.44 36.54 0.00 610150 34540 0 dm-1 0.05 1.10 0.00 0.00 1044 0 0 nvme0n1 15.30 661.23 38.71 0.00 625076 36589 0 nvme1n1 6352.42 240726.35 1036.47 0.00 227565845 979808 0 zram0 4189.65 4883.27 11876.36 0.00 4616304 11227080 0 total used free shared buff/cache available Mem: 31830 9529 509 0 21791 21867 Swap: 31829 6441 25388 Refault distance seriese (Your config with page idle flag disabled): ================================================================== Execution Results after 901 seconds ------------------------------------------------------------------ Executed Time (µs) Rate STOCK_LEVEL 4268 27060267967.7 0.16 txn/s ------------------------------------------------------------------ TOTAL 4268 27060267967.7 0.16 txn/s workingset_nodes 115394 workingset_refault_anon 144774 workingset_refault_file 41055081 workingset_activate_anon 8 workingset_activate_file 13194460 workingset_restore_anon 144629 workingset_restore_file 187419 workingset_nodereclaim 19598 memcg 66 /machine.slice/libpod-4866051af817731602b37017b0e71feb2a8f2cbaa949f577e0444af01b4f3b0c.scope/container node 0 12 213402 18054 1287510 0 0r 0e 0p 0r 15755e 0p 1 0r 0e 0p 0r 4771e 0p 2 0r 0e 0p 908r 6810e 0p 3 0r 0e 0p 0r 0e 3533888p 0 0 0 0 0 0 13 141209 10690 3571958 0 0 0 0 0 0 0 1 0 0 0 0 0 0 2 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 14 69327 1165064 34657 0 0 0 0 0 0 0 1 0 0 0 0 0 0 2 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 15 6404 21574 3363 0 953R 1773T 0 1263395R 3816639T 0 1 0R 0T 0 1164069R 1936973T 0 2 0R 0T 0 350041R 409121T 0 3 0R 3T 0 12305R 4767303T 0 3622197L 36916O 3338446Y 10409N 7120F 6945A avg-cpu: %user %nice %system %iowait %steal %idle 75.79 0.00 10.68 3.91 1.18 8.44 Device tps kB_read/s kB_wrtn/s kB_dscd/s kB_read kB_wrtn kB_dscd dm-0 12.66 547.71 38.73 0.00 526782 37248 0 dm-1 0.05 1.09 0.00 0.00 1044 0 0 nvme0n1 13.02 563.23 40.86 0.00 541708 39297 0 nvme1n1 4916.00 217529.48 1018.04 0.00 209217677 979136 0 zram0 1744.90 1970.86 5009.75 0.00 1895556 4818328 0 total used free shared buff/cache available Mem: 31830 11713 485 0 19630 19684 Swap: 31829 2847 28982 And still refault distance series is better, and refault is also lower for both anon/file pages. ------ I did some more test using MySQL and other workflow, no performance drop observed so far. And with a loop MongoDB test (keep running 900s test in loop) using my previous VM env (the SATA SSD vdb is using cache bypass so not a host cache issue here) I found one thing interesting (refs bit is set to 2 in config): Loop test using 6.7: STOCK_LEVEL 874 27246011368.3 0.03 txn/s STOCK_LEVEL 1533 27023181579.6 0.06 txn/s STOCK_LEVEL 1122 28044867987.6 0.04 txn/s STOCK_LEVEL 1032 27378070931.9 0.04 txn/s STOCK_LEVEL 1021 27612530579.1 0.04 txn/s STOCK_LEVEL 750 28076187896.3 0.03 txn/s STOCK_LEVEL 780 27519993034.8 0.03 txn/s Refault stat here: workingset_refault_anon 126369 workingset_refault_file 170389428 STOCK_LEVEL 750 27464016123.5 0.03 txn/s STOCK_LEVEL 780 27529550313.0 0.03 txn/s STOCK_LEVEL 750 28296286486.1 0.03 txn/s STOCK_LEVEL 690 27504193850.3 0.03 txn/s STOCK_LEVEL 716 28089360754.5 0.03 txn/s STOCK_LEVEL 607 27852180474.3 0.02 txn/s STOCK_LEVEL 689 27703367075.4 0.02 txn/s STOCK_LEVEL 630 28184685482.7 0.02 txn/s STOCK_LEVEL 450 28667721196.2 0.02 txn/s STOCK_LEVEL 450 28047985314.4 0.02 txn/s STOCK_LEVEL 450 28125609857.3 0.02 txn/s STOCK_LEVEL 420 27393478488.0 0.02 txn/s STOCK_LEVEL 420 27435537312.3 0.02 txn/s STOCK_LEVEL 420 29060748699.2 0.01 txn/s STOCK_LEVEL 420 28155584095.2 0.01 txn/s STOCK_LEVEL 420 27888635407.0 0.02 txn/s STOCK_LEVEL 420 27307856858.5 0.02 txn/s STOCK_LEVEL 420 28842280889.0 0.01 txn/s STOCK_LEVEL 390 27640696814.1 0.01 txn/s STOCK_LEVEL 420 28471605716.7 0.01 txn/s STOCK_LEVEL 420 27648174237.5 0.02 txn/s STOCK_LEVEL 420 27848217938.7 0.02 txn/s STOCK_LEVEL 420 27344698602.2 0.02 txn/s STOCK_LEVEL 420 27046819537.2 0.02 txn/s STOCK_LEVEL 420 27855626843.2 0.02 txn/s STOCK_LEVEL 420 27971873627.9 0.02 txn/s STOCK_LEVEL 420 28007014046.4 0.01 txn/s STOCK_LEVEL 420 28445164626.1 0.01 txn/s STOCK_LEVEL 420 27902621006.5 0.02 txn/s STOCK_LEVEL 420 28282574433.3 0.01 txn/s STOCK_LEVEL 390 27161599608.7 0.01 txn/s Using refault distance seriese: STOCK_LEVEL 2605 27120667462.8 0.10 txn/s STOCK_LEVEL 3000 27106854857.2 0.11 txn/s STOCK_LEVEL 2925 27066601064.4 0.11 txn/s STOCK_LEVEL 2757 27035248005.2 0.10 txn/s STOCK_LEVEL 1325 28053716046.8 0.05 txn/s STOCK_LEVEL 717 27455091366.3 0.03 txn/s STOCK_LEVEL 967 27404085208.2 0.04 txn/s Refault stat here: workingset_refault_anon 109337 workingset_refault_file 191249716 STOCK_LEVEL 716 27448213557.2 0.03 txn/s STOCK_LEVEL 807 28607974517.8 0.03 txn/s STOCK_LEVEL 760 28081442513.2 0.03 txn/s STOCK_LEVEL 745 28594555797.6 0.03 txn/s STOCK_LEVEL 450 27999536348.3 0.02 txn/s STOCK_LEVEL 598 27095531895.4 0.02 txn/s STOCK_LEVEL 711 27623112841.1 0.03 txn/s STOCK_LEVEL 540 28358770820.6 0.02 txn/s STOCK_LEVEL 480 27734277554.5 0.02 txn/s STOCK_LEVEL 450 27313906125.3 0.02 txn/s STOCK_LEVEL 480 27487299100.4 0.02 txn/s STOCK_LEVEL 480 27804589683.5 0.02 txn/s STOCK_LEVEL 480 28242205820.8 0.02 txn/s STOCK_LEVEL 480 27540680102.3 0.02 txn/s STOCK_LEVEL 450 27428645816.8 0.02 txn/s STOCK_LEVEL 480 27946866129.2 0.02 txn/s STOCK_LEVEL 480 27266068262.3 0.02 txn/s STOCK_LEVEL 450 27267487051.5 0.02 txn/s STOCK_LEVEL 480 27896369224.8 0.02 txn/s STOCK_LEVEL 480 28784662706.1 0.02 txn/s STOCK_LEVEL 450 27179853217.8 0.02 txn/s STOCK_LEVEL 480 28170594101.7 0.02 txn/s STOCK_LEVEL 450 28084651341.0 0.02 txn/s STOCK_LEVEL 480 27901608868.6 0.02 txn/s STOCK_LEVEL 480 27323790886.6 0.02 txn/s STOCK_LEVEL 480 28891008895.4 0.02 txn/s STOCK_LEVEL 480 27964563148.0 0.02 txn/s STOCK_LEVEL 450 27942421198.4 0.02 txn/s STOCK_LEVEL 480 28833968825.8 0.02 txn/s STOCK_LEVEL 480 28090975437.9 0.02 txn/s STOCK_LEVEL 480 27915246877.4 0.02 txn/s It seems the performance will drain as the test keep running (might be caused by MongoDB anon usage rising or DB internal caching/logging), that explains why for a long term test the performance gap seem to be smaller. The VM have a poor IO performance so the test run speed is much slower too, take a long time to warm up. But I think it's clear that refault distance series will boost the performance during warm up, and for long time workload it's also looking better, especially for low IO performance machines. I still can't explain about why workingset_refault is higher for the better case in the VM environment... I can resetup/reboot/randomize the test the the performance is same here. My guess is maybe related to readahead or some kernel space IO path issue? The actual IO usage is lower when refault distance series is applied. I notices a slight performance regression (1 - 3%) for pure in-mem FIO though, the "bulk series" I sent previous can help improve it. There is a bug in my previous V3 that will cause PID controller to lost control in long term (due to a bugged bit operation, my bad), which I've fixed in link above, I can send out new series if you think it's acceptable.
