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From: Andi Kleen <ak@linux.intel.com>
To: James Bottomley <James.Bottomley@suse.de>
Cc: Joe Eykholt <jeykholt@cisco.com>,
	"Nicholas A. Bellinger" <nab@linux-iscsi.org>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Eric Moore <Eric.Moore@lsi.com>,
	linux-scsi@vger.kernel.org, vasu.dev@intel.com,
	willy@linux.intel.com
Subject: Re: [PATCH] scsi, mptsas : drop scsi_host lock when calling mptsas_qcmd
Date: Fri, 17 Sep 2010 09:16:56 +0200	[thread overview]
Message-ID: <20100917071656.GA2644@gargoyle.ger.corp.intel.com> (raw)
In-Reply-To: <1284675416.26423.47.camel@mulgrave.site>

> Not really ... look at the code path (in scsi.c:scsi_dispatch_cmd()).
> We take the lock, then get the serial number (that would likley have to
> be replaced with an atomic), check the state, call trace, call

An atomic unfortunately usually doesn't scale much better than a spinlock.
I suspect serials would need to be made optional, e.g. 
computing them lazily if really needed.

-andi

  reply	other threads:[~2010-09-17  7:14 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-16 19:44 [PATCH] scsi, mptsas : drop scsi_host lock when calling mptsas_qcmd Tim Chen
2010-09-16 20:48 ` Nicholas A. Bellinger
2010-09-16 21:18   ` Tim Chen
2010-09-16 21:25   ` Andi Kleen
2010-09-16 21:24     ` James Bottomley
2010-09-16 23:25       ` Christoph Hellwig
2010-09-17  0:13         ` Nicholas A. Bellinger
2010-09-17  1:12           ` Vasu Dev
2010-09-16 21:34     ` Nicholas A. Bellinger
2010-09-16 21:44       ` Nicholas A. Bellinger
2010-09-16 21:48         ` Nicholas A. Bellinger
2010-09-16 22:00     ` Joe Eykholt
2010-09-16 22:16       ` James Bottomley
2010-09-17  7:16         ` Andi Kleen [this message]
2010-09-17 10:32           ` Bart Van Assche
2010-09-17 12:19             ` James Bottomley
2010-09-16 22:26       ` Tim Chen
2010-09-16 21:31   ` Vasu Dev

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