From: Thorsten Leemhuis <firstname.lastname@example.org>
To: Roman Gushchin <email@example.com>,
Valentin Schneider <firstname.lastname@example.org>
Cc: Josef Bacik <email@example.com>,
Subject: Re: [REGRESSION] 5-10% increase in IO latencies with nohz balance patch
Date: Fri, 18 Feb 2022 12:00:41 +0100 [thread overview]
Message-ID: <firstname.lastname@example.org> (raw)
Hi, this is your Linux kernel regression tracker speaking. Top-posting
for once, to make this easy accessible to everyone.
FWIW, this is a gentle reminder that I'm still tracking this regression.
Afaics nothing happened in the last few weeks.
If the discussion continued somewhere else, please let me know; you can
do this directly or simply tell my regression tracking bot yourself by
sending a reply to this mail with a paragraph containing a regzbot
command like "#regzbot monitor
If you think there are valid reasons to drop this regressions from the
tracking, let me know; you can do this directly or simply tell my
regression tracking bot yourself by sending a reply to this mail with a
paragraph containing a regzbot command like "#regzbot invalid: Some
explanation" (without the quotes).
Anyway: I'm putting it on back burner now to reduce the noise, as this
afaics is less important than other regressions:
#regzbot backburner: Culprit is hard to track down
You likely get two more mails like this after the next two merge
windows, then I'll drop it if I don't here anything back.
Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
P.S.: As the Linux kernel's regression tracker I'm getting a lot of
reports on my table. I can only look briefly into most of them and lack
knowledge about most of the areas they concern. I thus unfortunately
will sometimes get things wrong or miss something important. I hope
that's not the case here; if you think it is, don't hesitate to tell me
in a public reply, it's in everyone's interest to set the public record
On 13.01.22 17:57, Roman Gushchin wrote:
> On Thu, Jan 13, 2022 at 04:41:57PM +0000, Valentin Schneider wrote:
>> On 03/01/22 11:16, Josef Bacik wrote:
>>> On Wed, Dec 22, 2021 at 04:07:35PM +0000, Valentin Schneider wrote:
>>>> On 22/12/21 13:42, Thorsten Leemhuis wrote:
>>>>> What's the status here? Just wondering, because there hasn't been any
>>>>> activity in this thread since 11 days and the festive season is upon us.
>>>>> Was the discussion moved elsewhere? Or is this still a mystery? And if
>>>>> it is: how bad is it, does it need to be fixed before Linus releases 5.16?
>>>> I got to the end of bisect #3 yesterday, the incriminated commit doesn't
>>>> seem to make much sense but I've just re-tested it and there is a clear
>>>> regression between that commit and its parent (unlike bisect #1 and #2):
>>>> 2127d22509aec3a83dffb2a3c736df7ba747a7ce mm, slub: fix two bugs in slab_debug_trace_open()
>>>> write_clat_ns_p99 195395.92 199638.20 4797.01 2.17%
>>>> write_iops 17305.79 17188.24 250.66 -0.68%
>>>> write_clat_ns_p99 195543.84 199996.70 5122.88 2.28%
>>>> write_iops 17300.61 17241.86 251.56 -0.34%
>>>> write_clat_ns_p99 195543.84 200724.48 5122.88 2.65%
>>>> write_iops 17300.61 17246.63 251.56 -0.31%
>>>> write_clat_ns_p99 195543.84 200445.41 5122.88 2.51%
>>>> write_iops 17300.61 17215.47 251.56 -0.49%
>>>> 6d2aec9e123bb9c49cb5c7fc654f25f81e688e8c mm/mempolicy: do not allow illegal MPOL_F_NUMA_BALANCING | MPOL_LOCAL in mbind()
>>>> write_clat_ns_p99 195395.92 197942.30 4797.01 1.30%
>>>> write_iops 17305.79 17246.56 250.66 -0.34%
>>>> write_clat_ns_p99 195543.84 196183.92 5122.88 0.33%
>>>> write_iops 17300.61 17310.33 251.56 0.06%
>>>> write_clat_ns_p99 195543.84 196990.71 5122.88 0.74%
>>>> write_iops 17300.61 17346.32 251.56 0.26%
>>>> write_clat_ns_p99 195543.84 196362.24 5122.88 0.42%
>>>> write_iops 17300.61 17315.71 251.56 0.09%
>>>> It's pure debug stuff and AFAICT is a correct fix...
>>>> @Josef, could you test that on your side?
>>> Sorry, holidays and all that. I see 0 difference between the two commits, and
>>> no regression from baseline. It'll take me a few days to recover from the
>>> holidays, but I'll put some more effort into actively debugging wtf is going on
>>> here on my side since we're all having trouble pinning down what's going
>> Humph, that's unfortunate... I just came back from my holidays, so I'll be
>> untangling my inbox for the next few days. Do keep us posted!
> I'm trying to bisect it independently and make sense of it too, thanks to Josef
> for providing me a test setup. From the very first data I've got yesterday,
> the only thing I can say the data is very noisy and I'm not totally convinced
> that the regression is coming from the patch which was blamed initially.
> I hope to make more progress today/tomorrow, will keep you updated.
next prev parent reply other threads:[~2022-02-18 11:00 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-29 17:03 [REGRESSION] 5-10% increase in IO latencies with nohz balance patch Josef Bacik
2021-11-29 18:03 ` Valentin Schneider
2021-11-29 18:15 ` Josef Bacik
2021-11-29 18:31 ` Valentin Schneider
2021-11-29 19:49 ` Josef Bacik
2021-11-30 0:26 ` Valentin Schneider
2021-12-03 12:03 ` Valentin Schneider
2021-12-03 19:00 ` Josef Bacik
2021-12-06 9:48 ` Valentin Schneider
2021-12-09 17:22 ` Valentin Schneider
2021-12-09 19:16 ` Josef Bacik
2021-12-22 12:42 ` Thorsten Leemhuis
2021-12-22 16:07 ` Valentin Schneider
2022-01-03 16:16 ` Josef Bacik
2022-01-13 16:41 ` Valentin Schneider
2022-01-13 16:57 ` Roman Gushchin
2022-02-18 11:00 ` Thorsten Leemhuis [this message]
2022-02-18 15:34 ` Josef Bacik
2021-11-30 7:16 ` Thorsten Leemhuis
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