Re: udevd is killing file write performance.

[Nick Piggin]

John McCutchan wrote:
> On Fri, 2006-24-02 at 18:07 +1100, Nick Piggin wrote:

> > I saw this problem when testing my lockless pagecache a while back.
> >
> > Attached is a first implementation of what was my idea then of how
> > to solve it... note it is pretty rough and I never got around to doing
> > much testing of it.
> >
> > Basically: moves work out of inotify event time and to inotify attach
> > /detach time while staying out of the core VFS.
>
>
>
> This looks really good. There might be some corner cases but it looks
> like it will solve this problem nicely.

Thanks. You should see I sent a new version which fixes several bugs
and cleans up the code a bit.

There might be some areas of potential problems:
- creating and deleting watches on directories with many entries will
  take a long time. Is anyone likely to be creating and destroying
  these things at a very high frequency? Probably nobody cares except
  it might twist some real-time knickers.

- concurrent operations in the same watched directory will incur the
  same scalability penalty. I think this is basically a non-issue since
  the sheer number of events coming out will likely be a bigger problem.
  Doctor, it hurts when I do this.

--
SUSE Labs, Novell Inc.
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