From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [LSF/MM TOPIC] iSCSI MQ adoption via MCS discussion Date: Thu, 08 Jan 2015 15:11:28 +0100 Message-ID: <54AE9010.5080609@acm.org> References: <54AD5DDD.2090808@dev.mellanox.co.il> <54AD6563.4040603@suse.de> <54ADA777.6090801@cs.wisc.edu> <54AE36CE.8020509@acm.org> <54AE8A02.1030100@dev.mellanox.co.il> Reply-To: open-iscsi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Return-path: In-Reply-To: <54AE8A02.1030100-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org> List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: Sagi Grimberg , open-iscsi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, Hannes Reinecke , lsf-pc-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Cc: linux-scsi , target-devel , Oren Duer , Or Gerlitz List-Id: linux-scsi@vger.kernel.org On 01/08/15 14:45, Sagi Grimberg wrote: > Actually I started with that approach, but the independent connections > under a single session (I-T-Nexus) violates the command ordering > requirement. Plus, such a solution is specific to iSER... Hello Sagi, Which command ordering requirement are you referring to ? The Linux storage stack does not guarantee that block layer or SCSI commands will be processed in the same order as these commands have been submitted. However, it might be interesting to have a look at virtscsi_pick_vq(). I think the purpose of that function is to keep queueing to the same hwq as long as any commands are being executed. This approach avoids that if an application is migrated by the scheduler from one CPU to another that commands get reordered due to have been submitted to different hwq's. I don't think we already have something similar in blk-mq but this is something that could be discussed further. > (we might want to leave something for LSF ;)). Agreed :-) Bart. -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To unsubscribe from this group and stop receiving emails from it, send an email to open-iscsi+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To post to this group, send email to open-iscsi-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org Visit this group at http://groups.google.com/group/open-iscsi. For more options, visit https://groups.google.com/d/optout.