Minchan Kim writes: > On Thu, Jun 16, 2016 at 07:52:26AM +0800, Huang, Ying wrote: >> "Kirill A. Shutemov" 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" writes: >> >> > > >> >> > > > "Kirill A. Shutemov" 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: