From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44242) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yygib-00059X-5M for qemu-devel@nongnu.org; Sat, 30 May 2015 09:22:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YygiW-0004Ot-5f for qemu-devel@nongnu.org; Sat, 30 May 2015 09:22:29 -0400 Sender: Paolo Bonzini Message-ID: <5569B95A.6030202@redhat.com> Date: Sat, 30 May 2015 15:21:30 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <20150527090745.GA4669@noname.str.redhat.com> <55659372.9060804@redhat.com> <20150527101016.GB4669@noname.str.redhat.com> <55659FCC.2030704@redhat.com> <20150528024950.GC22609@dhcp-14-238.nay.redhat.com> <5566D076.8010807@redhat.com> <20150528104616.GA8461@dhcp-14-238.nay.redhat.com> <5566F36F.1010502@redhat.com> <20150528111124.GC8461@dhcp-14-238.nay.redhat.com> <5566F9AC.90102@redhat.com> <20150528120548.GH8461@dhcp-14-238.nay.redhat.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v6 01/13] block: Add op blocker type "device IO" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Andrey Korolyov , Fam Zheng Cc: Kevin Wolf , qemu block , "qemu-devel@nongnu.org" , jcody@redhat.com, Markus Armbruster , Max Reitz , Stefan Hajnoczi , Amit Shah On 29/05/2015 13:11, Andrey Korolyov wrote: > Sorry for a potential thread hijack, but I`m curious about the reasons > to not making advertised queue depth for non-passthrough backends an > independent tunable, is there any concerns behind that? It certainly can be made tunable. Usually it is bounded actually, for example PATA has a queue depth of 1 (!) while AHCI has 32. For virtio (blk and scsi) it actually is already somewhat tunable, since the queue depth is limited by the size of the virtqueue. Paolo