Messages in this thread |  | | Subject | Re: [LKP] Re: [ext4] b1b4705d54: filebench.sum_bytes_mb/s -20.2% regression | From | Xing Zhengjun <> | Date | Wed, 4 Mar 2020 16:15:38 +0800 |
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Hi Matthew,
We test it in v5.6-rc4, the issue still exist, do you have time to take a look at this? Thanks.
On 1/8/2020 10:31 AM, Rong Chen wrote: > > > On 1/8/20 1:28 AM, Jan Kara wrote: >> On Tue 07-01-20 11:57:08, Theodore Y. Ts'o wrote: >>> On Tue, Jan 07, 2020 at 02:41:06PM +0100, Jan Kara wrote: >>>> Hello, >>>> >>>> On Tue 24-12-19 08:59:15, kernel test robot wrote: >>>>> FYI, we noticed a -20.2% regression of filebench.sum_bytes_mb/s due >>>>> to commit: >>>>> >>>>> >>>>> commit: b1b4705d54abedfd69dcdf42779c521aa1e0fbd3 ("ext4: introduce >>>>> direct I/O read using iomap infrastructure") >>>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master >>>>> >>>>> in testcase: filebench >>>>> on test machine: 8 threads Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz >>>>> with 8G memory >>>>> with following parameters: >>>>> >>>>> disk: 1HDD >>>>> fs: ext4 >>>>> test: fivestreamreaddirect.f >>>>> cpufreq_governor: performance >>>>> ucode: 0x27 >>>> I was trying to reproduce this but I failed with my test VM. I had >>>> SATA SSD >>>> as a backing store though so maybe that's what makes a difference. >>>> Maybe >>>> the new code results in somewhat more seeks because the five threads >>>> which >>>> compete in submitting sequential IO end up being more interleaved? >>> A "-20.2% regression" should be read as a "20.2% performance >>> improvement" is zero-day kernel speak. >> Are you sure? I can see: >> >> 58.30 ± 2% -20.2% 46.53 filebench.sum_bytes_mb/s >> >> which implies to me previously the throughput was 58 MB/s and after the >> commit it was 46 MB/s? >> >> Anyway, in my testing that commit made no difference in that benchmark >> whasoever (getting around 97 MB/s for each thread before and after the >> commit). >> Honza > > We're sorry for the misunderstanding, "-20.2%" means the change of > filebench.sum_bytes_mb/s, > "regression" means the explanation of this change from LKP. > > Best Regards, > Rong Chen > _______________________________________________ > LKP mailing list -- lkp@lists.01.org > To unsubscribe send an email to lkp-leave@lists.01.org
-- Zhengjun Xing
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