OpenVZ Forum: Devel » [Q] missing unused dentry in prune

Home » Mailing lists » Devel » [Q] missing unused dentry in prune_dcache()?

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list [message #7914 is a reply to message #7910]

Mon, 30 October 2006 15:08

Eric Dumazet
Messages: 36
Registered: July 2006

Member

On Monday 30 October 2006 15:24, Vasily Averin wrote:
> Andrew Morton wrote:
> > On Fri, 27 Oct 2006 18:05:50 +0400
> >
> > Vasily Averin <vvs@sw.ru> wrote:
> >> Virtuozzo/OpenVZ linux kernel team has discovered that umount/remount
> >> can last for hours looping in shrink_dcache_sb() without much successes.
> >> Since during shrinking s_umount semaphore is taken lots of other
> >> unrelated operations like sync can stop working until shrink finished.
> >
> > Did you consider altering shrink_dcache_sb() so that it holds onto
> > dcache_lock and moves all the to-be-pruned dentries onto a private list
> > in a single pass, then prunes them all outside the lock?
>
> At the first glance it is wrong because of 2 reasons:
> 1) it continues to check the whole global LRU list (we propose to use
> per-sb LRU, it will provide very quick search)

Quick search maybe, but your patch adds 2 pointers to each dentry in the
system... That's pretty expensive, as dentries are already using a *lot* of
ram.

Maybe an alternative would be to not have anymore a global dentry_unused, but
only per-sb unused dentries lists ?

> 2) we have not any guarantee that someone will add new unused dentries to
> the list when we prune it outside the lock. And to the contrary, some of
> unused dentries can be used again. As far as I understand we should hold
> dcache_lock beginning at the removing dentry from unused_list until
> dentry_iput() call.
>
> David did it inside shrink_dcache_for_umount() just because it have
> guarantee that all the filesystem operations are finished and new ones
> cannot be started.

Report message to a moderator

[Message index]

		[Q] missing unused dentry in prune_dcache()? By: vaverin on Wed, 25 October 2006 12:30
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Wed, 25 October 2006 13:58
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Wed, 25 October 2006 14:23
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Thu, 26 October 2006 11:36
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Thu, 26 October 2006 13:25
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Fri, 27 October 2006 08:05
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Fri, 27 October 2006 10:42
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Fri, 27 October 2006 11:50
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Fri, 27 October 2006 12:11
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Fri, 27 October 2006 13:47
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Fri, 27 October 2006 14:29
		Re: [Q] missing unused dentry in prune_dcache()? By: dev on Fri, 27 October 2006 14:34
		[PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: vaverin on Fri, 27 October 2006 14:05
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Andrew Morton on Fri, 27 October 2006 18:06
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: vaverin on Mon, 30 October 2006 14:24
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Eric Dumazet on Mon, 30 October 2006 15:08
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: dev on Mon, 30 October 2006 15:27
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Eric Dumazet on Mon, 30 October 2006 16:09
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: dev on Mon, 30 October 2006 15:06
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: David Chinner on Mon, 30 October 2006 04:24
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: dev on Mon, 30 October 2006 06:22
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Neil Brown on Tue, 31 October 2006 04:38
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: David Howells on Tue, 31 October 2006 10:40
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Neil Brown on Wed, 01 November 2006 06:32
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: vaverin on Wed, 01 November 2006 13:32
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Neil Brown on Tue, 14 November 2006 05:44
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: vaverin on Tue, 14 November 2006 06:12
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: vaverin on Tue, 31 October 2006 13:08
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: dev on Wed, 01 November 2006 10:48
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Neil Brown on Tue, 14 November 2006 04:51
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: David Howells on Tue, 14 November 2006 09:29
		[PATCH 2.6.19-rc3] VFS: missing unused dentry in prune_dcache() By: vaverin on Fri, 27 October 2006 13:42
		Re: [PATCH 2.6.19-rc3] VFS: missing unused dentry in prune_dcache() By: David Howells on Fri, 27 October 2006 14:24
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Wed, 25 October 2006 13:51
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Thu, 26 October 2006 11:49
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Thu, 26 October 2006 12:33
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Thu, 26 October 2006 13:23
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Thu, 26 October 2006 13:58
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Thu, 26 October 2006 14:07
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Fri, 27 October 2006 06:32
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Fri, 27 October 2006 06:50
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Fri, 27 October 2006 09:36
		[Q] missing ->d_delete() in shrink_dcache_for_umount()? By: vaverin on Tue, 31 October 2006 13:24
		Re: [Q] missing ->d_delete() in shrink_dcache_for_umount()? By: David Howells on Tue, 31 October 2006 15:06

Previous Topic:	[PATCH]: OOM can panic due to processes stuck in __alloc_pages()
Next Topic:	[PATCH] move_task_off_dead_cpu() should be called with disabled ints

Goto Forum:

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Sun Aug 24 07:37:01 GMT 2025

Total time taken to generate the page: 0.05684 seconds