From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: use_clustering (sht) bit set to 0 in AHCI ? Date: Thu, 24 May 2007 23:06:04 -0400 Message-ID: <4656529C.4050701@garzik.org> References: <35f686220704252249y6d4fe0c3y1a772119c7b6657f@mail.gmail.com> <20070521121726.GT14746@kernel.dk> <46520C68.7090105@garzik.org> <20070522074538.GP4705@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:50683 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753291AbXEYDGJ (ORCPT ); Thu, 24 May 2007 23:06:09 -0400 In-Reply-To: <20070522074538.GP4705@kernel.dk> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jens Axboe Cc: Alok kataria , linux-ide@vger.kernel.org Jens Axboe wrote: > On Mon, May 21 2007, Jeff Garzik wrote: >> Jens Axboe wrote: >>> ahci has always had clustering disabled, perhaps Jeff can expand on why? >> >> Just historical reasons. libata had clustering disabled by default in >> the beginning, for all drivers. Then we enabled it globally by changing >> the value of ATA_SHT_USE_CLUSTERING... but apparently forgot to change >> drivers which use their own value rather than ATA_SHT_USE_CLUSTERING. >> >> Feel free to submit a patch turning it on... > > The below works for me, but it's only lightly tested. I booted it up and > ran some large IO tests, I've verified really large IO sizes as well > (using blktrace, I've verified ios up to 9216KiB being accepted and > completed by the drive). > > ----- > > From: Jens Axboe > > ahci: enable sg segment clustering > > The specification states that ahci supports segments up to 4MiB in size, > so enable clustering. > > Signed-off-by: Jens Axboe applied