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Subject: Re: [BENCHMARK] max bomb segment tuning with read latency 2 patch
	in  contest
From: GrandMasterLee <masterlee@digitalroadkill.net>
To: Andrew Morton <akpm@digeo.com>
Cc: Con Kolivas <conman@kolivas.net>,
       linux kernel mailing list <linux-kernel@vger.kernel.org>
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On Fri, 2002-12-06 at 23:55, Andrew Morton wrote:
[...]
> If the SMP machine is using scsi then that tends to make the elevator
> changes less effective.  Because the disk sort-of has its own internal
> elevator which in my testing on a Fujitsu disk has the same ill-advised
> design as the kernel's elevator: it treats reads and writes in a similar
> manner.
> 
> Setting the tag depth to zero helps heaps.

Command tag queue? As in the compile time option? Or do you mean queue
depth?(or are they the same)

> But as you're interested in `desktop responsiveness' you should be
> mostly testing against IDE disks.  Their behavour tends to be quite
> different.
> 
> If you can turn on write caching on the SCSI disks that would change
> the picture too.

Just for clarity, What about for something like FC attached storage
Where the controllers enforce cache policies on a "per volume" basis?
Would that == the same thing? 



--The GrandMaster
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