Messages in this thread |  | | Subject | Re: [LKP] Re: [ext4] b1b4705d54: filebench.sum_bytes_mb/s -20.2% regression | From | Xing Zhengjun <> | Date | Wed, 25 Mar 2020 13:50:09 +0800 |
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ping... The issue still exists in v5.6-rc7.
On 3/4/2020 4:15 PM, Xing Zhengjun wrote: > 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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