From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boaz Harrosh Subject: Re: [GIT PATCH] another tranche of SCSI updates for 2.6.26 Date: Mon, 28 Apr 2008 15:24:12 +0300 Message-ID: <4815C1EC.7090109@panasas.com> References: <1209320076.3801.26.camel@localhost.localdomain> <20080428013400.GA6245@elte.hu> <1209351113.3801.107.camel@localhost.localdomain> <48157B6A.60307@panasas.com> <1209384784.3367.1.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from DSL212-235-53-3.bb.netvision.net.il ([212.235.53.3]:56351 "EHLO bh-buildlin2.bhalevy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932260AbYD1OsE (ORCPT ); Mon, 28 Apr 2008 10:48:04 -0400 In-Reply-To: <1209384784.3367.1.camel@localhost.localdomain> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Ingo Molnar , Andrew Morton , Linus Torvalds , linux-scsi , linux-kernel On Mon, Apr 28 2008 at 15:13 +0300, James Bottomley wrote: > On Mon, 2008-04-28 at 10:23 +0300, Boaz Harrosh wrote: >> If we are already on the subject. It looks like we always have at most 1 command in the >> free list, so why the free list at all? or am I reading the code wrong? > > Because list handlers are well understood mechanisms within the kernel. This is not an excuse ;-). So is a simple pointer. > Also because in low memory situations, one command per host is > sufficient to guarantee forward progress, but it's not going to be very > efficient. Embedded and other low memory environments can increase the > size of the free list to improve their I/O path. > Ok that is what I thought, but inspecting the code, I can't find it. Is there a config option or an external mechanism that let you do that? If not, is/was there a ready made external patch that will enable such facility in someway? Should there be one? > James > Boaz