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Date: Fri, 17 Jun 2016 14:41:56 +0900
From: Minchan Kim <minchan@...nel.org>
To: "Huang, Ying" <ying.huang@...el.com>
CC: "Kirill A. Shutemov" <kirill@...temov.name>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Rik van Riel <riel@...hat.com>,
Michal Hocko <mhocko@...e.com>,
LKML <linux-kernel@...r.kernel.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Michal Hocko <mhocko@...nel.org>,
Vinayak Menon <vinmenon@...eaurora.org>,
Mel Gorman <mgorman@...e.de>,
Andrew Morton <akpm@...ux-foundation.org>, <lkp@...org>
Subject: Re: [LKP] [lkp] [mm] 5c0a85fad9: unixbench.score -6.3% regression
On Thu, Jun 16, 2016 at 03:27:44PM -0700, Huang, Ying wrote:
> Minchan Kim <minchan@...nel.org> writes:
>
> > On Thu, Jun 16, 2016 at 07:52:26AM +0800, Huang, Ying wrote:
> >> "Kirill A. Shutemov" <kirill@...temov.name> writes:
> >>
> >> > On Tue, Jun 14, 2016 at 05:57:28PM +0900, Minchan Kim wrote:
> >> >> On Wed, Jun 08, 2016 at 11:58:11AM +0300, Kirill A. Shutemov wrote:
> >> >> > On Wed, Jun 08, 2016 at 04:41:37PM +0800, Huang, Ying wrote:
> >> >> > > "Huang, Ying" <ying.huang@...el.com> writes:
> >> >> > >
> >> >> > > > "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com> writes:
> >> >> > > >
> >> >> > > >> On Mon, Jun 06, 2016 at 10:27:24AM +0800, kernel test robot wrote:
> >> >> > > >>>
> >> >> > > >>> FYI, we noticed a -6.3% regression of unixbench.score due to commit:
> >> >> > > >>>
> >> >> > > >>> commit 5c0a85fad949212b3e059692deecdeed74ae7ec7 ("mm: make faultaround produce old ptes")
> >> >> > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> >> >> > > >>>
> >> >> > > >>> in testcase: unixbench
> >> >> > > >>> on test machine: lituya: 16 threads Haswell High-end Desktop (i7-5960X 3.0G) with 16G memory
> >> >> > > >>> with following parameters: cpufreq_governor=performance/nr_task=1/test=shell8
> >> >> > > >>>
> >> >> > > >>>
> >> >> > > >>> Details are as below:
> >> >> > > >>> -------------------------------------------------------------------------------------------------->
> >> >> > > >>>
> >> >> > > >>>
> >> >> > > >>> =========================================================================================
> >> >> > > >>> compiler/cpufreq_governor/kconfig/nr_task/rootfs/tbox_group/test/testcase:
> >> >> > > >>> gcc-4.9/performance/x86_64-rhel/1/debian-x86_64-2015-02-07.cgz/lituya/shell8/unixbench
> >> >> > > >>>
> >> >> > > >>> commit:
> >> >> > > >>> 4b50bcc7eda4d3cc9e3f2a0aa60e590fedf728c5
> >> >> > > >>> 5c0a85fad949212b3e059692deecdeed74ae7ec7
> >> >> > > >>>
> >> >> > > >>> 4b50bcc7eda4d3cc 5c0a85fad949212b3e059692de
> >> >> > > >>> ---------------- --------------------------
> >> >> > > >>> fail:runs %reproduction fail:runs
> >> >> > > >>> | | |
> >> >> > > >>> 3:4 -75% :4 kmsg.DHCP/BOOTP:Reply_not_for_us,op[#]xid[#]
> >> >> > > >>> %stddev %change %stddev
> >> >> > > >>> \ | \
> >> >> > > >>> 14321 . 0% -6.3% 13425 . 0% unixbench.score
> >> >> > > >>> 1996897 . 0% -6.1% 1874635 . 0% unixbench.time.involuntary_context_switches
> >> >> > > >>> 1.721e+08 . 0% -6.2% 1.613e+08 . 0% unixbench.time.minor_page_faults
> >> >> > > >>> 758.65 . 0% -3.0% 735.86 . 0% unixbench.time.system_time
> >> >> > > >>> 387.66 . 0% +5.4% 408.49 . 0% unixbench.time.user_time
> >> >> > > >>> 5950278 . 0% -6.2% 5583456 . 0% unixbench.time.voluntary_context_switches
> >> >> > > >>
> >> >> > > >> That's weird.
> >> >> > > >>
> >> >> > > >> I don't understand why the change would reduce number or minor faults.
> >> >> > > >> It should stay the same on x86-64. Rise of user_time is puzzling too.
> >> >> > > >
> >> >> > > > unixbench runs in fixed time mode. That is, the total time to run
> >> >> > > > unixbench is fixed, but the work done varies. So the minor_page_faults
> >> >> > > > change may reflect only the work done.
> >> >> > > >
> >> >> > > >> Hm. Is reproducible? Across reboot?
> >> >> > > >
> >> >> > >
> >> >> > > And FYI, there is no swap setup for test, all root file system including
> >> >> > > benchmark files are in tmpfs, so no real page reclaim will be
> >> >> > > triggered. But it appears that active file cache reduced after the
> >> >> > > commit.
> >> >> > >
> >> >> > > 111331 . 1% -13.3% 96503 . 0% meminfo.Active
> >> >> > > 27603 . 1% -43.9% 15486 . 0% meminfo.Active(file)
> >> >> > >
> >> >> > > I think this is the expected behavior of the commit?
> >> >> >
> >> >> > Yes, it's expected.
> >> >> >
> >> >> > After the change faularound would produce old pte. It means there's more
> >> >> > chance for these pages to be on inactive lru, unless somebody actually
> >> >> > touch them and flip accessed bit.
> >> >>
> >> >> Hmm, tmpfs pages should be in anonymous LRU list and VM shouldn't scan
> >> >> anonymous LRU list on swapless system so I really wonder why active file
> >> >> LRU is shrunk.
> >> >
> >> > Hm. Good point. I don't why we have anything on file lru if there's no
> >> > filesystems except tmpfs.
> >> >
> >> > Ying, how do you get stuff to the tmpfs?
> >>
> >> We put root file system and benchmark into a set of compressed cpio
> >> archive, then concatenate them into one initrd, and finally kernel use
> >> that initrd as initramfs.
> >
> > I see.
> >
> > Could you share your 4 full vmstat(/proc/vmstat) files?
> >
> > old:
> >
> > cat /proc/vmstat > before.old.vmstat
> > do benchmark
> > cat /proc/vmstat > after.old.vmstat
> >
> > new:
> >
> > cat /proc/vmstat > before.new.vmstat
> > do benchmark
> > cat /proc/vmstat > after.new.vmstat
> >
> > IOW, I want to see stats related to reclaim.
>
> Hi,
>
> The /proc/vmstat for the parent commit (parent-proc-vmstat.gz) and first
> bad commit (fbc-proc-vmstat.gz) are attached with the email.
>
> The contents of the file is more than the vmstat before and after
> benchmark running, but are sampled every 1 seconds. Every sample begin
> with "time: <time>". You can check the first and last samples. The
> first /proc/vmstat capturing is started at the same time of the
> benchmark, so it is not exactly the vmstat before the benchmark running.
>
Thanks for the testing!
nr_active_file was shrunk 48% but the vaule itself is not huge so
I don't think it affects performance a lot.
There was no reclaim activity for testing. :(
pgfault, 6% reduced. Given that, pgalloc/free reduced 6%, too
because unixbench was time fixed mode and 6% regressed so no
doubt.
No interesting data.
It seems you tested it with THP, maybe always mode?
I'm so sorry but could you test it with disabling CONFIG_TRANSPARENT_HUGEPAGE=n
again? it might you already did.
Is it still 6% regressed with disabling THP?
nr_free_pages -6663 -6461 96.97%
nr_alloc_batch 2594 4013 154.70%
nr_inactive_anon 112 112 100.00%
nr_active_anon 2536 2159 85.13%
nr_inactive_file -567 -227 40.04%
nr_active_file 648 315 48.61%
nr_unevictable 0 0 0.00%
nr_mlock 0 0 0.00%
nr_anon_pages 2634 2161 82.04%
nr_mapped 511 530 103.72%
nr_file_pages 207 215 103.86%
nr_dirty -7 -6 85.71%
nr_writeback 0 0 0.00%
nr_slab_reclaimable 158 328 207.59%
nr_slab_unreclaimable 2208 2115 95.79%
nr_page_table_pages 268 247 92.16%
nr_kernel_stack 143 80 55.94%
nr_unstable 1 1 100.00%
nr_bounce 0 0 0.00%
nr_vmscan_write 0 0 0.00%
nr_vmscan_immediate_reclaim 0 0 0.00%
nr_writeback_temp 0 0 0.00%
nr_isolated_anon 0 0 0.00%
nr_isolated_file 0 0 0.00%
nr_shmem 131 131 100.00%
nr_dirtied 67 78 116.42%
nr_written 74 84 113.51%
nr_pages_scanned 0 0 0.00%
numa_hit 483752446 453696304 93.79%
numa_miss 0 0 0.00%
numa_foreign 0 0 0.00%
numa_interleave 0 0 0.00%
numa_local 483752445 453696304 93.79%
numa_other 1 0 0.00%
workingset_refault 0 0 0.00%
workingset_activate 0 0 0.00%
workingset_nodereclaim 0 0 0.00%
nr_anon_transparent_hugepages 1 0 0.00%
nr_free_cma 0 0 0.00%
nr_dirty_threshold -1316 -1274 96.81%
nr_dirty_background_threshold -658 -637 96.81%
pgpgin 0 0 0.00%
pgpgout 0 0 0.00%
pswpin 0 0 0.00%
pswpout 0 0 0.00%
pgalloc_dma 0 0 0.00%
pgalloc_dma32 60130977 56323630 93.67%
pgalloc_normal 457203182 428863437 93.80%
pgalloc_movable 0 0 0.00%
pgfree 517327743 485181251 93.79%
pgactivate 2059556 1930950 93.76%
pgdeactivate 0 0 0.00%
pgfault 572723351 537107146 93.78%
pgmajfault 0 0 0.00%
pglazyfreed 0 0 0.00%
pgrefill_dma 0 0 0.00%
pgrefill_dma32 0 0 0.00%
pgrefill_normal 0 0 0.00%
pgrefill_movable 0 0 0.00%
pgsteal_kswapd_dma 0 0 0.00%
pgsteal_kswapd_dma32 0 0 0.00%
pgsteal_kswapd_normal 0 0 0.00%
pgsteal_kswapd_movable 0 0 0.00%
pgsteal_direct_dma 0 0 0.00%
pgsteal_direct_dma32 0 0 0.00%
pgsteal_direct_normal 0 0 0.00%
pgsteal_direct_movable 0 0 0.00%
pgscan_kswapd_dma 0 0 0.00%
pgscan_kswapd_dma32 0 0 0.00%
pgscan_kswapd_normal 0 0 0.00%
pgscan_kswapd_movable 0 0 0.00%
pgscan_direct_dma 0 0 0.00%
pgscan_direct_dma32 0 0 0.00%
pgscan_direct_normal 0 0 0.00%
pgscan_direct_movable 0 0 0.00%
pgscan_direct_throttle 0 0 0.00%
zone_reclaim_failed 0 0 0.00%
pginodesteal 0 0 0.00%
slabs_scanned 0 0 0.00%
kswapd_inodesteal 0 0 0.00%
kswapd_low_wmark_hit_quickly 0 0 0.00%
kswapd_high_wmark_hit_quickly 0 0 0.00%
pageoutrun 0 0 0.00%
allocstall 0 0 0.00%
pgrotated 0 0 0.00%
drop_pagecache 0 0 0.00%
drop_slab 0 0 0.00%
numa_pte_updates 0 0 0.00%
numa_huge_pte_updates 0 0 0.00%
numa_hint_faults 0 0 0.00%
numa_hint_faults_local 0 0 0.00%
numa_pages_migrated 0 0 0.00%
pgmigrate_success 0 0 0.00%
pgmigrate_fail 0 0 0.00%
compact_migrate_scanned 0 0 0.00%
compact_free_scanned 0 0 0.00%
compact_isolated 0 0 0.00%
compact_stall 0 0 0.00%
compact_fail 0 0 0.00%
compact_success 0 0 0.00%
compact_daemon_wake 0 0 0.00%
htlb_buddy_alloc_success 0 0 0.00%
htlb_buddy_alloc_fail 0 0 0.00%
unevictable_pgs_culled 0 0 0.00%
unevictable_pgs_scanned 0 0 0.00%
unevictable_pgs_rescued 0 0 0.00%
unevictable_pgs_mlocked 0 0 0.00%
unevictable_pgs_munlocked 0 0 0.00%
unevictable_pgs_cleared 0 0 0.00%
unevictable_pgs_stranded 0 0 0.00%
thp_fault_alloc 22731 21604 95.04%
thp_fault_fallback 0 0 0.00%
thp_collapse_alloc 1 0 0.00%
thp_collapse_alloc_failed 0 0 0.00%
thp_split_page 0 0 0.00%
thp_split_page_failed 0 0 0.00%
thp_deferred_split_page 22731 21604 95.04%
thp_split_pmd 0 0 0.00%
thp_zero_page_alloc 0 0 0.00%
thp_zero_page_alloc_failed 0 0 0.00%
balloon_inflate 0 0 0.00%
balloon_deflate 0 0 0.00%
balloon_migrate 0 0 0.00%
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