From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([65.50.211.133]:41393 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751144AbdHEIkw (ORCPT ); Sat, 5 Aug 2017 04:40:52 -0400 Date: Sat, 5 Aug 2017 01:40:49 -0700 From: "hch@infradead.org" To: Bart Van Assche Cc: "ming.lei@redhat.com" , "linux-scsi@vger.kernel.org" , "hch@infradead.org" , "jejb@linux.vnet.ibm.com" , "linux-block@vger.kernel.org" , "axboe@fb.com" , "loberman@redhat.com" , "martin.petersen@oracle.com" Subject: Re: [PATCH 04/14] blk-mq-sched: improve dispatching from sw queue Message-ID: <20170805084048.GA6643@infradead.org> References: <20170731165111.11536-1-ming.lei@redhat.com> <20170731165111.11536-6-ming.lei@redhat.com> <1501544074.2466.29.camel@wdc.com> <20170801101718.GB31452@ming.t460p> <20170801105013.GD31452@ming.t460p> <1501600301.2475.1.camel@wdc.com> <20170802033135.GB7267@ming.t460p> <1501724126.30887.3.camel@wdc.com> <20170803031344.GA8327@ming.t460p> <1501781583.2922.12.camel@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1501781583.2922.12.camel@wdc.com> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Thu, Aug 03, 2017 at 05:33:13PM +0000, Bart Van Assche wrote: > Are you aware that the SCSI core already keeps track of the number of busy requests > per LUN? See also the device_busy member of struct scsi_device. How about giving the > block layer core access in some way to that counter? I'd love ot move it to blk-mq in a scalable way eventually, as we'll run into the same problems with NVMe systems with multiple namespaces.