Re: Article in Phoronix about loss of performance in 2.6.35 releasecandidates

From: Ingo Molnar
Date: Tue Jun 01 2010 - 02:18:06 EST



* Pekka Enberg <penberg@xxxxxxxxxxxxxx> wrote:

> On Tue, Jun 1, 2010 at 7:10 AM, <tytso@xxxxxxx> wrote:
> > On Tue, Jun 01, 2010 at 12:19:29AM +0100, Alex Buell wrote:
> >> http://www.phoronix.com/vr.php?view=14976
> >>
> >> Question: Why?
> >
> > One of the theories that has been advanced is that it's simply this
> > problem:
> >
> > ? ? ? ?http://lkml.org/lkml/2010/5/22/154
> >
> > If so, it points out how idiotic Phoronix is about not being able to
> > notice udev pegging the CPU at 100% being someone bad for its
> > benchmark runs. ?:-)
> >
> > OTOH, this bug has been known for over a week, and it is sort sad that
> > we haven't reverted this patch. ?It looks like the conversation has
> > died, but without a fix?
>
> It's fixed by 1eb2cbb6d5efe129 so the problem doesn't exist for 2.6.35-r1.

Btw., the changelog in 1eb2cbb6d5efe129:

| From 1eb2cbb6d5efe129cd006691267ce513c0aa59da Mon Sep 17 00:00:00 2001
| From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
| Date: Thu, 27 May 2010 11:11:06 -0400
| Subject: [PATCH] Revert "anon_inode: set S_IFREG on the anon_inode"
|
| This reverts commit a7cf4145bb86aaf85d4d4d29a69b50b688e2e49d.
| ---
| fs/anon_inodes.c | 2 +-
| 1 files changed, 1 insertions(+), 1 deletions(-)

Is lacking pretty much all essential pieces of information which are required
for reverts:

- it has no description about who reported the bug.

- it has no description about what the problem was and what the effects were.
People have little chance to link up the 'udev is spinning' bug to
this fix.

- it has no link back to '3836a03: anon_inodes: mark the anon inode private'
which introduced it and hence it has no -stable tag either.

- has no signoff line

Ingo
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