Message-ID: <470BABAC.2030706@msgid.tls.msk.ru>
Date: Tue, 09 Oct 2007 20:26:20 +0400
From: Michael Tokarev <mjt@tls.msk.ru>
Organization: Telecom Service, JSC
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To: Boaz Harrosh <bharrosh@panasas.com>
CC: Andi Kleen <andi@firstfloor.org>, Michael Stiller <ms@2scale.net>,
       linux-kernel@vger.kernel.org
Subject: Re: howto boost write(2) performance?
References: <1191937817.3641.9.camel@blackberry> <p73odf849rq.fsf@bingen.suse.de> <470BA14C.90608@panasas.com>
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Boaz Harrosh wrote:
[]
> If your target is a SCSI target you can gain up to 15% by using
> sg. Search on the net for the "sg utils" package. The source code
> of sg_dd and others are a grate example of how to do it.
> 
> Other wise O_DIRECT is your friend. Also look for asynchronous
> I/O so you have a few pending IO buffers to keep the pipes full.

What's the advantage of sg_io over O_DIRECT to the block device?
I think sg devices are being (slowly?) obsoleted since most stuff
which has been in sg now works over normal block device, no?
At least, I haven't seen any significant difference between
sg_dd and dd with oflag=direct.

Thanks.

/mjt
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