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Re: nfs performance delta between filesystems

To: bpm@xxxxxxx
Subject: Re: nfs performance delta between filesystems
From: Emmanuel Florac <eflorac@xxxxxxxxxxxxxx>
Date: Fri, 22 Jan 2010 21:46:24 +0100
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20100122183848.GB28561@xxxxxxx>
Organization: Intellique
References: <20100122185419.63ae6430@xxxxxxxxxxxxxxxxxxxx> <20100122183848.GB28561@xxxxxxx>
Le Fri, 22 Jan 2010 12:38:48 -0600 vous écriviez:

> There were small gains to be had by reordering the sync of the parent
> and child syncs where the two inodes were in the same cluster.  The
> larger problem seemed to be that we're not treating the log as stable
> storage. By calling write_inode_now we've written the changes to the
> log first and then gone and also written them out to the inode.  

I thought that using nobarrier would prevent the log operations to be
sync'd to disk too quickly? Could I possibly enhance this behaviour by
using an external log on a very fast storage (ramdisk...)?

> nfsd_create, nfsd_link, and nfsd_setattr all do this (or do in the old
> kernel I'm looking at).  I have a patchset that changes
> this to an fsync so we force the log and call it good.  I'll be happy
> to dust it off if someone hasn't already addressed this situation.

Well, if you think this patchset can be applied to a current kernel
without too much hacking I'm ready to give it a try :)

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