Re: rename() contention (BUG?)

[Avi Kivity]

Josef Sipek wrote:
> On Wed, Oct 25, 2006 at 03:56:34PM -0500, lkml@xxxxxxxxxxx wrote:
>   
> > Hello,
> >
> > I have seen some scalability problems with Maildir-based mail systems running on
> > Linux (debian sarge, 2.6.8), and after much investigation I found a large part
> > of the problem was rename() contention.
> >     
>  
> Just FYI, around 2.6.15 the i_sem was replace with i_mutex which is much
> better/faster. (And I would strongly suggest you upgrade.) I would actually
> like to know how much the lock contention decresed for your case.
>   

The changes make the mutex more efficient, but won't decrease the 
contention.  It seems that all renames in one filesystem are serialized, 
and if the renames require I/O (which is certainly the case with nfs), 
rename throughput is severely limited.


--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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