Amir Goldstein writes: > On Sat, Jul 31, 2021 at 9:20 AM kernel test robot wrote: >> >> >> >> Greeting, >> >> FYI, we noticed a -3.3% regression of unixbench.score due to commit: >> >> >> commit: 4c40d6efc8b22b88a45c335ffd6d25b55d769f5b ("[PATCH v4 08/16] fsnotify: pass arguments of fsnotify() in struct fsnotify_event_info") >> url: https://github.com/0day-ci/linux/commits/Gabriel-Krisman-Bertazi/File-system-wide-monitoring/20210721-001444 >> base: https://git.kernel.org/cgit/linux/kernel/git/jack/linux-fs.git fsnotify >> >> in testcase: unixbench >> on test machine: 96 threads 2 sockets Intel(R) Xeon(R) CPU @ 2.30GHz with 128G memory >> with following parameters: >> >> runtime: 300s >> nr_task: 1 >> test: pipe >> cpufreq_governor: performance >> ucode: 0x4003006 >> >> test-description: UnixBench is the original BYTE UNIX benchmark suite aims to test performance of Unix-like system. >> test-url: https://github.com/kdlucas/byte-unixbench >> >> In addition to that, the commit also has significant impact on the following tests: >> >> +------------------+-------------------------------------------------------------------------------------+ >> | testcase: change | will-it-scale: will-it-scale.per_thread_ops -1.3% regression | >> | test machine | 192 threads 4 sockets Intel(R) Xeon(R) Platinum 9242 CPU @ 2.30GHz with 192G memory | >> | test parameters | cpufreq_governor=performance | >> | | mode=thread | >> | | nr_task=100% | >> | | test=eventfd1 | >> | | ucode=0x5003006 | >> +------------------+-------------------------------------------------------------------------------------+ >> >> >> If you fix the issue, kindly add following tag >> Reported-by: kernel test robot >> > > Gabriel, > > It looks like my change throws away much of the performance gain for > small IO on pipes without any watches that was achieved by commit > 71d734103edf ("fsnotify: Rearrange fast path to minimise overhead > when there is no watcher"). > > I think the way to fix it is to lift the optimization in __fsnotify() > to the fsnotify_parent() inline wrapper as Mel considered doing > but was not sure it was worth the effort at the time. > > It's not completely trivial. I think it requires setting a flag > MNT_FSNOTIFY_WATCHED when there are watches on the > vfsmount. I will look into it. Amir, Since this patch is a clean up, would you mind if I drop it from my series and base my work on top of mainline? Eventually, we can rebase this patch, when the performance issue is addressed. I ask because I'm about to send a v5 and I'm not sure if I should wait to have this fixed. -- Gabriel Krisman Bertazi