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Re: [Q] missing unused dentry in prune_dcache()? [message #7809 is a reply to message #7791]

Thu, 26 October 2006 11:36

vaverin
Messages: 708
Registered: September 2005

Senior Member

Hello David

David Howells wrote:
> Vasily Averin <vvs@sw.ru> wrote:
>>>> The patch adds this dentry into tail of the dentry_unused list.
>>> I think that's reasonable. I wonder if we can avoid removing it from the
>>> list in the first place, but I suspect it's less optimal.
>> Could you please explain this place in details, I do not understand why tail
>> of the list is better than head. Also I do not understand why we should go
>> to out in this case. Why we cannot use next dentry in the list instead?
>
> I meant adding it back into the list is reasonable; I didn't actually consider
> where you were adding it back.
>
> So, given that the three ops that affect this are very unlikely to be happening
> at any one time, it's probably worth just slapping it at the head and ignoring
> it. The main thing is that it's reinserted somewhere.

I don't like to insert this dentry into tail of list because of it prevents
shrink_dcache_memory. It finds "skipped" dentry at the tail of the list, does
not free it and goes to out without any progress.

Therefore I've removed break of cycle and insert this dentry to head of the
list. Theoretically it can lead to the second using of the same dentry, however
I do not think that it is a big problem.

Signed-off-by: Vasily Averin <vvs@sw.ru>

--- linux-2.6.19-rc3/fs/dcache.c.prdch 2006-10-25 16:09:19.000000000 +0400
+++ linux-2.6.19-rc3/fs/dcache.c 2006-10-26 15:14:51.000000000 +0400
@@ -478,11 +478,9 @@ static void prune_dcache(int count, stru
up_read(s_umount);
}
spin_unlock(&dentry->d_lock);
- /* Cannot remove the first dentry, and it isn't appropriate
- * to move it to the head of the list, so give up, and try
- * later
- */
- break;
+ /* Inserting dentry to tail of the list leads to cycle */
+ list_add(&dentry->d_lru, &dentry_unused);
+ dentry_stat.nr_unused++;
}
spin_unlock(&dcache_lock);
}

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[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

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