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From: Minchan Kim <minchan@kernel.org>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Rik van Riel <riel@redhat.com>, Michal Hocko <mhocko@suse.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>,
	Vinayak Menon <vinmenon@codeaurora.org>,
	Mel Gorman <mgorman@suse.de>,
	Andrew Morton <akpm@linux-foundation.org>, <lkp@01.org>
Subject: Re: [LKP] [lkp] [mm] 5c0a85fad9: unixbench.score -6.3% regression
Date: Fri, 17 Jun 2016 14:41:56 +0900	[thread overview]
Message-ID: <20160617054156.GB2374@bbox> (raw)
In-Reply-To: <87a8ikkbvj.fsf@yhuang-mobile.sh.intel.com>

On Thu, Jun 16, 2016 at 03:27:44PM -0700, Huang, Ying wrote:
> Minchan Kim <minchan@kernel.org> writes:
> 
> > On Thu, Jun 16, 2016 at 07:52:26AM +0800, Huang, Ying wrote:
> >> "Kirill A. Shutemov" <kirill@shutemov.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@intel.com> writes:
> >> >> > > 
> >> >> > > > "Kirill A. Shutemov" <kirill.shutemov@linux.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%

  reply	other threads:[~2016-06-17  5:42 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-06  2:27 kernel test robot
2016-06-06  9:51 ` Kirill A. Shutemov
2016-06-08  7:21   ` [LKP] " Huang, Ying
2016-06-08  8:41     ` Huang, Ying
2016-06-08  8:58       ` Kirill A. Shutemov
2016-06-12  0:49         ` Huang, Ying
2016-06-12  1:02           ` Linus Torvalds
2016-06-13  9:02             ` Huang, Ying
2016-06-14 13:38               ` Minchan Kim
2016-06-15 23:42                 ` Huang, Ying
2016-06-13 12:52             ` Kirill A. Shutemov
2016-06-14  6:11               ` Linus Torvalds
2016-06-14  8:26                 ` Kirill A. Shutemov
2016-06-14 16:07                   ` Rik van Riel
2016-06-14 14:03                 ` Christian Borntraeger
2016-06-14  8:57         ` Minchan Kim
2016-06-14 14:34           ` Kirill A. Shutemov
2016-06-15 23:52             ` Huang, Ying
2016-06-16  0:13               ` Minchan Kim
2016-06-16 22:27                 ` Huang, Ying
2016-06-17  5:41                   ` Minchan Kim [this message]
2016-06-17 19:26                     ` Huang, Ying
2016-06-20  0:06                       ` Minchan Kim

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