From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [PATCH RFC] virtio: use QUEUE_FLAG_CLUSTER in virtio_blk Date: Mon, 17 Nov 2008 17:22:43 +1030 Message-ID: <200811171722.43792.rusty@rustcorp.com.au> References: <200811141215.33950.rusty@rustcorp.com.au> <20081114093023.GQ26778@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20081114093023.GQ26778@kernel.dk> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Jens Axboe Cc: kvm-devel , Anthony Liguori , virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org On Friday 14 November 2008 20:00:23 Jens Axboe wrote: > Queue clustering is on by default though when you allocate your queue, > so I'm surprised you see a difference by doing: > > + /* Gather adjacent buffers to minimize sg length. */ > + queue_flag_set(QUEUE_FLAG_CLUSTER, vblk->disk->queue); > > did test_bit(QUEUE_FLAG_CLUSTER, &vblk->disk->queue->queue_flags) really > return 0 before? Apparently not. My results must be noise :( However, it made me look harder at the behaviour of the driver. I have two other enhancement patches while I'll send now, but I still only see sgs of 116 elements. Thanks for the clue donation, Rusty.