RE: Bluestore tuning

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If the oNode cache is based on oNode count, then we might want to rethink the accounting as the oNode size is likely to be highly variable meaning that the memory consumption of the cache will be highly variable too. This means that users will have to set the cache for the worst-case oNode size, meaning that most of the time the actual oNode cache will be much smaller than desired -- for the resources (DRAM) that's involved.

Allen Samuels
SanDisk |a Western Digital brand
2880 Junction Avenue, Milpitas, CA 95134
T: +1 408 801 7030| M: +1 408 780 6416
allen.samuels@xxxxxxxxxxx

> -----Original Message-----
> From: ceph-devel-owner@xxxxxxxxxxxxxxx [mailto:ceph-devel-
> owner@xxxxxxxxxxxxxxx] On Behalf Of Evgeniy Firsov
> Sent: Thursday, July 28, 2016 1:35 AM
> To: Somnath Roy <Somnath.Roy@xxxxxxxxxxx>; Kamble, Nitin A
> <Nitin.Kamble@xxxxxxxxxxxx>
> Cc: Mark Nelson (mnelson@xxxxxxxxxx) <mnelson@xxxxxxxxxx>; ceph-
> devel@xxxxxxxxxxxxxxx
> Subject: Re: Bluestore tuning
> 
> Somnath,
> 
> In my opinion, ³memory leak² may be just onode cache size grows.
> By default its 16K entries per PG (8 by default), onode size is ~38K for 4M RBD
> object, so its 5.1G by default.
> Likely you use much more Pgs.
> Disabling checksums, reducing RBD object size will reduce the cache size.
> 
> On 7/27/16, 10:26 PM, "ceph-devel-owner@xxxxxxxxxxxxxxx on behalf of
> Somnath Roy" <ceph-devel-owner@xxxxxxxxxxxxxxx on behalf of
> Somnath.Roy@xxxxxxxxxxx> wrote:
> 
> >My ceph version is 11.0.0-811-g278ea12, it is ~3-4 days old master.
> >Regarding stability , it is getting there , no more easy crashes seen
> >:-) I am getting a memory leak though in the write path and after 1
> >hour of continuous run (4K RW) memory is started swapping for me..I am
> >trying to nail it down..
> >
> >Thanks & Regards
> >Somnath
> >
> >
> >-----Original Message-----
> >From: Kamble, Nitin A [mailto:Nitin.Kamble@xxxxxxxxxxxx]
> >Sent: Wednesday, July 27, 2016 10:19 PM
> >To: Somnath Roy
> >Cc: Mark Nelson (mnelson@xxxxxxxxxx); ceph-devel@xxxxxxxxxxxxxxx
> >Subject: Re: Bluestore tuning
> >
> >Hi Somnath,
> >  Thanks for sharing this information. And great to see bluestore with
> >improved stability and performance. Which version of ceph were you
> >running in this environment, latest master?
> >Also it would be good to know the level of stability of the environment.
> >Did ceph cluster broke after collection of this data?
> >
> >Thanks,
> >Nitin
> >
> >> On Jul 27, 2016, at 8:40 AM, Somnath Roy <Somnath.Roy@xxxxxxxxxxx>
> >>wrote:
> >>
> >> As discussed in performance meeting, I am sharing the latest
> >>Bluestore tuning findings that is giving me better and most
> >>importantly stable result in my environment.
> >>
> >> Setup :
> >> -------
> >>
> >> 2 OSD nodes with 8 OSDs (on 8 TB SSD) each.
> >> Single 4TB image (with exclusive lock disabled) from single client
> >>running 10 fio jobs and each job is with 128 QD.
> >> Replication = 2.
> >> Fio rbd ran for 30 min.
> >>
> >> Ceph.conf
> >> ------------
> >>        osd_op_num_threads_per_shard = 2
> >>        osd_op_num_shards = 25
> >>
> >>        bluestore_rocksdb_options =
> >>"max_write_buffer_number=16,min_write_buffer_number_to_merge=2
> ,recycle
> >>_lo
> >>g_file_num=16,compaction_threads=32,flusher_threads=8,max_backgro
> und_c
> >>omp
> >>actions=32,max_background_flushes=8,max_bytes_for_level_base=5368
> 70912
> >>0,w
> >>rite_buffer_size=83886080,level0_file_num_compaction_trigger=4,level0
> _
> >>slo wdown_writes_trigger=400,level0_stop_writes_trigger=800"
> >>
> >>        rocksdb_cache_size = 4294967296
> >>        bluestore_csum = false
> >>        bluestore_csum_type = none
> >>        bluestore_bluefs_buffered_io = false
> >>        bluestore_max_ops = 30000
> >>        bluestore_max_bytes = 629145600
> >>        bluestore_buffer_cache_size = 104857600
> >>        bluestore_block_wal_size = 0
> >>
> >> [osd.0]
> >>       host = emsnode12
> >>       devs = /dev/sdb1
> >>       #osd_journal = /dev/sdb1
> >>       bluestore_block_db_path = /dev/sdb2
> >>       #bluestore_block_wal_path = /dev/nvme0n1p1
> >>       bluestore_block_wal_path = /dev/sdb3
> >>       bluestore_block_path = /dev/sdb4
> >>
> >> I have separate partition for block/db/wal..
> >>
> >> Result:
> >> --------
> >> No preconditioning of rbd images , started writing 4K RW from the
> >>beginning.
> >>
> >> Jobs: 10 (f=10): [w(10)] [100.0% done] [0KB/150.3MB/0KB /s]
> >>[0/38.5K/0  iops] [eta 00m:00s]
> >> rbd_iodepth32: (groupid=0, jobs=10): err= 0: pid=883598: Fri Jul 22
> >> 19:43:41 2016
> >>  write: io=282082MB, bw=160473KB/s, iops=40118, runt=1800007msec
> >>    slat (usec): min=25, max=2578, avg=51.73, stdev=15.99
> >>    clat (usec): min=585, max=2096.7K, avg=3913.59, stdev=9871.73
> >>     lat (usec): min=806, max=2096.7K, avg=3965.32, stdev=9871.71
> >>    clat percentiles (usec):
> >>     |  1.00th=[ 1208],  5.00th=[ 1480], 10.00th=[ 1672], 20.00th=[
> >>1992],
> >>     | 30.00th=[ 2288], 40.00th=[ 2608], 50.00th=[ 2992], 60.00th=[
> >>3440],
> >>     | 70.00th=[ 4048], 80.00th=[ 4960], 90.00th=[ 6624], 95.00th=[
> >>8384],
> >>     | 99.00th=[15680], 99.50th=[25984], 99.90th=[55552],
> >>99.95th=[64256],
> >>     | 99.99th=[87552]
> >>    bw (KB  /s): min=    7, max=33864, per=10.08%, avg=16183.08,
> >>stdev=1401.82
> >>    lat (usec) : 750=0.01%, 1000=0.10%
> >>    lat (msec) : 2=20.39%, 4=48.81%, 10=27.70%, 20=2.30%, 50=0.55%
> >>    lat (msec) : 100=0.14%, 250=0.01%, 2000=0.01%, >=2000=0.01%
> >>  cpu          : usr=20.18%, sys=3.67%, ctx=96626924, majf=0, minf=166692
> >>  IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=27.0%, 16=73.0%, 32=0.0%,
> >>>=64=0.0%
> >>     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%,
> >>>=64=0.0%
> >>     complete  : 0=0.0%, 4=99.9%, 8=0.1%, 16=0.1%, 32=0.0%, 64=0.0%,
> >>>=64=0.0%
> >>     issued    : total=r=0/w=72213031/d=0, short=r=0/w=0/d=0
> >>     latency   : target=0, window=0, percentile=100.00%, depth=16
> >>
> >> *Significantly better latency/throughput than similar setup filestore*.
> >>
> >>
> >> This is based on my experiment on all SSD , HDD case will be different.
> >> Tuning also depends on your cpu complex/memory, I am running with 48
> >>core (HT enabled) dual socket Xeon on each node with 64GB of memory..
> >>
> >> Thanks & Regards
> >> Somnath
> >>
> >> -----Original Message-----
> >> From: Somnath Roy
> >> Sent: Monday, July 11, 2016 8:04 AM
> >> To: Mark Nelson (mnelson@xxxxxxxxxx)
> >> Cc: 'ceph-devel@xxxxxxxxxxxxxxx'
> >> Subject: Rocksdb tuning on Bluestore
> >>
> >> Mark,
> >> With the following tuning it seems rocksdb is performing better in my
> >>environment. Basically, doing aggressive compaction to reduce the
> >>write stalls.
> >>
> >> bluestore_rocksdb_options =
> >>"max_write_buffer_number=16,min_write_buffer_number_to_merge=1
> 6,recycl
> >>e_l
> >>og_file_num=16,compaction_threads=32,flusher_threads=4,max_backgr
> ound_
> >>com
> >>pactions=32,max_background_flushes=8,max_bytes_for_level_base=536
> 87091
> >>20,
> >>write_buffer_size=83886080,level0_file_num_compaction_trigger=4,level
> 0
> >>_sl owdown_writes_trigger=400,level0_stop_writes_trigger=800"
> >>
> >>
> >> BTW, I am not able to run BlueStore more than 2 hour at a stretch due
> >>to memory issues. It is filling up my system memory (2 node of 64 G
> >>memory , running 8 OSDS on each) fast.
> >> The following operation I did and it started swapping.
> >>
> >> 1. Created a 4TB image and did 1M sequential preconditioning (took ~1
> >> hour)
> >>
> >> 2. Followed by two 30 min 4k RW with QD 128 (numjob = 10) and in the
> >>2nd run memory started swapping.
> >>
> >> Let me know how this rocksdb option works for you.
> >>
> >> Thanks & Regards
> >> Somnath
> >>
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