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. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
