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Re: [dm-devel] [PATCHSET block#for-2.6.36-post] block: replace barrier with sequenced flush



Christoph Hellwig wrote:
> On Mon, Aug 23, 2010 at 04:01:15PM +0200, Jens Axboe wrote:
>> The problem purely exists on arrays that report write back cache enabled
>> AND don't implement SYNC_CACHE as a noop. Do any of them exist, or are
>> they purely urban legend?
> 
> I haven't seen it.  I don't care particularly about this case, but once
> it a while people want to disable flushing for testing or because they
> really don't care.
> 
aacraid for one falls into this category.
SYNC_CACHE is no-oped in the driver. Otherwise you get a _HUGE_
performance loss.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare suse de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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