From: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: target-devel <target-devel@vger.kernel.org>,
linux-scsi <linux-scsi@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Christoph Hellwig <hch@lst.de>,
"Martin K. Petersen" <martin.petersen@oracle.com>
Subject: Re: [PATCH 2/3] target: Add max_write_same_len device attribute
Date: Thu, 15 Nov 2012 11:23:12 -0800 [thread overview]
Message-ID: <1353007392.4447.22.camel@haakon2.linux-iscsi.org> (raw)
In-Reply-To: <20121115105312.GC28956@infradead.org>
On Thu, 2012-11-15 at 05:53 -0500, Christoph Hellwig wrote:
> On Thu, Nov 08, 2012 at 08:07:17PM +0000, Nicholas A. Bellinger wrote:
> > From: Nicholas Bellinger <nab@linux-iscsi.org>
> >
> > This patch adds a new max_write_same_len device attribute for use with
> > WRITE_SAME w/ UNMAP=0 backend emulation.
> >
> > Also, update block limits VPD emulation code in spc_emulate_evpd_b0() to
> > set the default MAXIMUM WRITE SAME LENGTH value of zero.
>
> why do we need an exposed attribute for this?
>
This is useful for userspace to reduce the allowed maximum from the
default 0xFFFF set by IBLOCK. Allowing huge WRITE_SAMEs can very much
effect performance (esp. with spinning media), so being able to reduce
the max we accept via a userspace tunable is helpful.
--nab
next prev parent reply other threads:[~2012-11-15 19:23 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-08 20:07 [PATCH 0/3] target/iblock: Add WRITE_SAME w/ UNMAP=0 emulation Nicholas A. Bellinger
2012-11-08 20:07 ` [PATCH 1/3] target/sbc: Make WRITE_SAME check differentiate between UNMAP=[1,0] Nicholas A. Bellinger
2012-11-15 10:52 ` Christoph Hellwig
2012-11-08 20:07 ` [PATCH 2/3] target: Add max_write_same_len device attribute Nicholas A. Bellinger
2012-11-15 10:53 ` Christoph Hellwig
2012-11-15 19:23 ` Nicholas A. Bellinger [this message]
2012-11-16 13:05 ` Paolo Bonzini
2012-11-08 20:07 ` [PATCH 3/3] target/iblock: Add WRITE_SAME w/ UNMAP=0 emulation support Nicholas A. Bellinger
2012-11-15 11:04 ` Christoph Hellwig
2012-11-15 15:03 ` Douglas Gilbert
2012-11-15 15:25 ` Martin K. Petersen
2012-11-15 19:29 ` Nicholas A. Bellinger
2012-11-15 19:32 ` Christoph Hellwig
2012-11-15 20:01 ` Elliott, Robert (Server Storage)
2012-11-15 20:31 ` Nicholas A. Bellinger
2012-11-19 11:38 ` Paolo Bonzini
2012-11-19 23:19 ` Elliott, Robert (Server Storage)
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