From: Linus Torvalds <torvalds@linux-foundation.org>
To: Akemi Yagi <toracat@elrepo.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
David Howells <dhowells@redhat.com>
Subject: Re: [PATCH 0/2] pipe: Fixes [ver #2]
Date: Sun, 8 Dec 2019 10:04:51 -0800 [thread overview]
Message-ID: <CAHk-=wgteio3DVccVPZrD-dd9BNDM5128EQqCFxaEOb4Eu9H=w@mail.gmail.com> (raw)
In-Reply-To: <CABA31DrsaqT-TsOVx=kbRBnuM5He53+=NLgwm94swY-x1UPjuA@mail.gmail.com>
On Sun, Dec 8, 2019 at 8:46 AM Akemi Yagi <toracat@elrepo.org> wrote:
>
> I forgot to mention that the aforementioned bug in make was originally
> reported for Fedora. They now have a patched version of make
> (make-4.2.1-15.fc32) in Rawhide.
Yes, as mentioned I do expect it's some jobserver interaction - I've
seen bad jobserver behavior before. But my 'make' hasn't been upgraded
since May, as far as I can tell from my logs, so the huge performance
regression was new.
So the huge slowdown is real, and was triggered by the kernel changes.
But yes, it's entirely possible - even likely - that it's due to a
jobserver bug that ends up being sensitive to scheduling.
We do treat even "user space is buggy and shouldn't have done that" as
a regression.
It's annoying. Timing-related issues are some of the worst to debug.
Particularly when (at least I) primarily debug by looking at the code
and trying to see what's wrong that way.
Linus
next prev parent reply other threads:[~2019-12-08 18:05 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-05 22:30 [PATCH 0/2] pipe: Fixes [ver #2] David Howells
2019-12-05 22:30 ` [PATCH 1/2] pipe: Remove assertion from pipe_poll() " David Howells
2019-12-05 22:30 ` [PATCH 2/2] pipe: Fix missing mask update after pipe_wait() " David Howells
2019-12-05 23:58 ` Linus Torvalds
2019-12-06 13:56 ` [PATCH 0/2] pipe: Fixes " David Sterba
2019-12-06 17:09 ` Linus Torvalds
2019-12-06 17:42 ` Linus Torvalds
2019-12-06 18:59 ` Linus Torvalds
2019-12-07 21:31 ` Akemi Yagi
2019-12-08 16:45 ` Akemi Yagi
2019-12-08 18:04 ` Linus Torvalds [this message]
2019-12-09 3:07 ` Linus Torvalds
2019-12-06 20:28 ` Linus Torvalds
2019-12-06 21:04 ` Linus Torvalds
2019-12-07 3:50 ` Linus Torvalds
2019-12-07 4:01 ` Linus Torvalds
2019-12-07 22:47 ` Linus Torvalds
2019-12-09 9:53 ` Vincent Guittot
2019-12-09 17:48 ` Linus Torvalds
2019-12-09 17:57 ` Akemi Yagi
2019-12-09 18:18 ` Linus Torvalds
2019-12-09 18:24 ` Linus Torvalds
2019-12-18 20:59 ` Josh Triplett
2019-12-10 2:58 ` DJ Delorie
2019-12-10 14:38 ` Vincent Guittot
2019-12-10 17:39 ` Linus Torvalds
2019-12-11 18:09 ` DJ Delorie
2019-12-11 18:59 ` Linus Torvalds
2019-12-12 10:18 ` Konstantin Khlebnikov
2019-12-18 22:51 ` Linus Torvalds
2019-12-19 0:03 ` Josh Triplett
2019-12-19 0:14 ` Josh Triplett
2019-12-19 0:51 ` Linus Torvalds
2019-12-19 0:54 ` Linus Torvalds
2019-12-19 7:56 ` David Howells
2019-12-19 16:35 ` Linus Torvalds
2019-12-11 20:55 ` David Howells
2019-12-12 1:28 ` Linus Torvalds
2019-12-12 7:34 ` David Howells
2019-12-09 14:55 ` David Sterba
2019-12-06 21:26 ` David Howells
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