Hi Jan,
Am 25.08.22 um 11:18 schrieb Jan Kara:
Hi Stefan!
On Wed 24-08-22 23:24:43, Stefan Wahren wrote:
Am 24.08.22 um 12:40 schrieb Jan Kara:
Hi Stefan!
On Wed 24-08-22 12:17:14, Stefan Wahren wrote:
Am 23.08.22 um 22:15 schrieb Jan Kara:
Hello,
So I have implemented mballoc improvements to avoid spreading allocations
even with mb_optimize_scan=1. It fixes the performance regression I was able
to reproduce with reaim on my test machine:
mb_optimize_scan=0 mb_optimize_scan=1 patched
Hmean disk-1 2076.12 ( 0.00%) 2099.37 ( 1.12%) 2032.52 ( -2.10%)
Hmean disk-41 92481.20 ( 0.00%) 83787.47 * -9.40%* 90308.37 ( -2.35%)
Hmean disk-81 155073.39 ( 0.00%) 135527.05 * -12.60%* 154285.71 ( -0.51%)
Hmean disk-121 185109.64 ( 0.00%) 166284.93 * -10.17%* 185298.62 ( 0.10%)
Hmean disk-161 229890.53 ( 0.00%) 207563.39 * -9.71%* 232883.32 * 1.30%*
Hmean disk-201 223333.33 ( 0.00%) 203235.59 * -9.00%* 221446.93 ( -0.84%)
Hmean disk-241 235735.25 ( 0.00%) 217705.51 * -7.65%* 239483.27 * 1.59%*
Hmean disk-281 266772.15 ( 0.00%) 241132.72 * -9.61%* 263108.62 ( -1.37%)
Hmean disk-321 265435.50 ( 0.00%) 245412.84 * -7.54%* 267277.27 ( 0.69%)
Stefan, can you please test whether these patches fix the problem for you as
well? Comments & review welcome.
i tested the whole series against 5.19 and 6.0.0-rc2. In both cases the
update process succeed which is a improvement, but the download + unpack
duration ( ~ 7 minutes ) is not as good as with mb_optimize_scan=0 ( ~ 1
minute ).
OK, thanks for testing! I'll try to check specifically untar whether I can
still see some differences in the IO pattern on my test machine.
i made two iostat output logs during the complete download phase with 5.19
and your series applied. iostat was running via ssh connection and
rpi-update via serial console.
First with mb_optimize_scan=0
https://github.com/lategoodbye/mb_optimize_scan_regress/blob/main/5.19_SDCIT_patch_nooptimize_download_success.iostat.log
Second with mb_optimize_scan=1
https://github.com/lategoodbye/mb_optimize_scan_regress/blob/main/5.19_SDCIT_patch_optimize_download_success.iostat.log
Maybe this helps
Thanks for the data! So this is interesting. In both iostat logs, there is
initial phase where no IO happens. I guess that's expected. It is
significantly longer in the mb_optimize_scan=0 but I suppose that is just
caused by a difference in when iostat was actually started. Then in
mb_optimize_scan=0 there is 155 seconds where the eMMC card is 100%
utilized and then iostat ends. During this time ~63MB is written
altogether. Request sizes vary a lot, average is 60KB.
In mb_optimize_scan=1 case there is 715 seconds recorded where eMMC card is
100% utilized. During this time ~133MB is written, average request size is
40KB. If I look just at first 155 seconds of the trace (assuming iostat was
in both cases terminated before writing was fully done), we have written
~53MB and average request size is 56KB.
So with mb_optimize_scan=1 we are indeed still somewhat slower but based on
the trace it is not clear why the download+unpack should take 7 minutes
instead of 1 minute. There must be some other effect we are missing.
Perhaps if you just download the archive manually, call sync(1), and measure
how long it takes to (untar the archive + sync) in mb_optimize_scan=0/1 we
can see whether plain untar is indeed making the difference or there's
something else influencing the result as well (I have checked and
rpi-update does a lot of other deleting & copying as the part of the
update)? Thanks.
I will provide those iostats.
Btw i untar the firmware archive (mb_optimized_scan=1 and your patch)
and got following:
cat /proc/fs/ext4/mmcblk1p2/mb_structs_summary
optimize_scan: 1
max_free_order_lists:
list_order_0_groups: 5
list_order_1_groups: 0
list_order_2_groups: 0
list_order_3_groups: 0
list_order_4_groups: 1
list_order_5_groups: 0
list_order_6_groups: 1
list_order_7_groups: 1
list_order_8_groups: 10
list_order_9_groups: 1
list_order_10_groups: 2
list_order_11_groups: 0
list_order_12_groups: 2
list_order_13_groups: 55
fragment_size_tree:
tree_min: 1
tree_max: 31249
tree_nodes: 79
Is this expected?
Honza
