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To: Chris Mason <mason@suse.com>
cc: Steve Lord <lord@sgi.com>, Jeremy Hansen <jeremy@xxedgexx.com>,
        linux-kernel@vger.kernel.org
Subject: Re: scsi vs ide performance on fsync's 
In-Reply-To: Message from Chris Mason <mason@suse.com> 
   of "Fri, 02 Mar 2001 14:38:56 EST." <412990000.983561936@tiny> 
Date: Fri, 02 Mar 2001 13:41:02 -0600
From: Steve Lord <lord@sgi.com>
Sender: linux-kernel-owner@vger.kernel.org
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> 
> 
> On Friday, March 02, 2001 01:25:25 PM -0600 Steve Lord <lord@sgi.com> wrote:
> 
> >> For why ide is beating scsi in this benchmark...make sure tagged queueing
> >> is on (or increase the queue length?).  For the xlog.c test posted, I
> >> would expect scsi to get faster than ide as the size of the write
> >> increases.
> > 
> > I think the issue is the call being used now is going to get slower the
> > larger the device is, just from the point of view of how many buffers it
> > has to scan.
> 
> filemap_fdatawait, filemap_fdatasync, and fsync_inode_buffers all restrict
> their scans to a list of dirty buffers for that specific file.  Only
> file_fsync goes through all the dirty buffers on the device, and the ext2
> fsync path never calls file_fsync.
> 
> Or am I missing something?
> 
> -chris
> 
> 

No you are not, I will now go put on the brown paper bag.....

The scsi thing is wierd though, we have seen it here too.

Steve



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