| Message ID | 20220908091301.147-1-jack@suse.cz |
|---|---|
| Headers | show |
| Series | ext4: Fix performance regression with mballoc | expand |
Hi Jan, Am 08.09.22 um 11:21 schrieb Jan Kara: > Hello, > > Here is the third version of my mballoc improvements to avoid spreading > allocations with mb_optimize_scan=1. Since v2 there are only small changes and > fixes found during review and testing. Overall the series looks mostly ready to > go, I just didn't see any comments regarding patch 3 - a fix of metabg handling > in the Orlov allocator which is kind of independent, I've just found it when > reading the code. Also patch 5 needs final review after all the fixes. > > Changes since v1: > - reworked data structure for CR 1 scan > - make small closed files use locality group preallocation > - fix metabg handling in the Orlov allocator > > Changes since v2: > - whitespace fixes > - fix outdated comment > - fix handling of mb_structs_summary procfs file > - fix bad unlock on error recovery path unfortunately the real patches doesn't have v3 which leads to confusion. Just a note: in case this series cannot be applied for stable (5.15), we need a second solution to fix the regression there.
On Thu 08-09-22 12:36:10, Stefan Wahren wrote: > Hi Jan, > > Am 08.09.22 um 11:21 schrieb Jan Kara: > > Hello, > > > > Here is the third version of my mballoc improvements to avoid spreading > > allocations with mb_optimize_scan=1. Since v2 there are only small changes and > > fixes found during review and testing. Overall the series looks mostly ready to > > go, I just didn't see any comments regarding patch 3 - a fix of metabg handling > > in the Orlov allocator which is kind of independent, I've just found it when > > reading the code. Also patch 5 needs final review after all the fixes. > > > > Changes since v1: > > - reworked data structure for CR 1 scan > > - make small closed files use locality group preallocation > > - fix metabg handling in the Orlov allocator > > > > Changes since v2: > > - whitespace fixes > > - fix outdated comment > > - fix handling of mb_structs_summary procfs file > > - fix bad unlock on error recovery path > > unfortunately the real patches doesn't have v3 which leads to confusion. Yeah, OK, I've updated my scripting for posting patches to include version in each posted patch :) > Just a note: in case this series cannot be applied for stable (5.15), we > need a second solution to fix the regression there. My plan is to backport the current series. It is not that invasive so it should be doable... Honza
Hi Jan, Am 09.09.22 um 12:40 schrieb Jan Kara: > On Thu 08-09-22 12:36:10, Stefan Wahren wrote: >> Hi Jan, >> >> Am 08.09.22 um 11:21 schrieb Jan Kara: >>> Hello, >>> >>> Here is the third version of my mballoc improvements to avoid spreading >>> allocations with mb_optimize_scan=1. Since v2 there are only small changes and >>> fixes found during review and testing. Overall the series looks mostly ready to >>> go, I just didn't see any comments regarding patch 3 - a fix of metabg handling >>> in the Orlov allocator which is kind of independent, I've just found it when >>> reading the code. Also patch 5 needs final review after all the fixes. >>> >>> Changes since v1: >>> - reworked data structure for CR 1 scan >>> - make small closed files use locality group preallocation >>> - fix metabg handling in the Orlov allocator >>> >>> Changes since v2: >>> - whitespace fixes >>> - fix outdated comment >>> - fix handling of mb_structs_summary procfs file >>> - fix bad unlock on error recovery path >> unfortunately the real patches doesn't have v3 which leads to confusion. > Yeah, OK, I've updated my scripting for posting patches to include version > in each posted patch :) > >> Just a note: in case this series cannot be applied for stable (5.15), we >> need a second solution to fix the regression there. > My plan is to backport the current series. It is not that invasive so it > should be doable... This would be great. Btw i retested this version and i can confirm the procfs crash is fixed. > > Honza
Hello, Here is the third version of my mballoc improvements to avoid spreading allocations with mb_optimize_scan=1. Since v2 there are only small changes and fixes found during review and testing. Overall the series looks mostly ready to go, I just didn't see any comments regarding patch 3 - a fix of metabg handling in the Orlov allocator which is kind of independent, I've just found it when reading the code. Also patch 5 needs final review after all the fixes. Changes since v1: - reworked data structure for CR 1 scan - make small closed files use locality group preallocation - fix metabg handling in the Orlov allocator Changes since v2: - whitespace fixes - fix outdated comment - fix handling of mb_structs_summary procfs file - fix bad unlock on error recovery path Original cover letter: The patches fix 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%) The changes also significanly reduce spreading of allocations for small / moderately sized files. I'm not able to measure a performance difference resulting from this but on eMMC storage this seems to be the main culprit of reduced performance. Untarring of raspberry-pi archive touches following numbers of groups: mb_optimize_scan=0 mb_optimize_scan=1 patched groups 4 22 7 To achieve this I have added two more changes on top of v1 - patches 4 and 5. Patch 4 makes sure we use locality group preallocation even for files that are not likely to grow anymore (previously we have disabled all preallocations for such files, however locality group preallocation still makes a lot of sense for such files). This patch reduced spread of a small file allocations but larger file allocations were still spread significantly because they avoid locality group preallocation and as they are not power-of-two in size, they also immediately start with cr=1 scan. To address that I've changed the data structure for looking up the best block group to allocate from (see patch 5 for details). Honza Previous versions: Link: http://lore.kernel.org/r/20220823134508.27854-1-jack@suse.cz # v1 Link: http://lore.kernel.org/r/20220906150803.375-1-jack@suse.cz # v2