From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Kashyap Desai References: <20180313094243.8710-1-ming.lei@redhat.com> <20180313094243.8710-2-ming.lei@redhat.com> <1521460114.4592.29.camel@intel.com> <1521470529.4592.51.camel@gmail.com> In-Reply-To: <1521470529.4592.51.camel@gmail.com> MIME-Version: 1.0 Date: Mon, 19 Mar 2018 20:25:19 +0530 Message-ID: <7f8105c04bde47637eadf043ef04b9bf@mail.gmail.com> Subject: RE: [PATCH V5 1/5] scsi: hpsa: fix selection of reply queue To: dedekind1@gmail.com, hch@lst.de, Thomas Gleixner Cc: linux-block@vger.kernel.org, snitzer@redhat.com, hare@suse.de, mroos@linux.ee, linux-scsi@vger.kernel.org, don.brace@microsemi.com, pbonzini@redhat.com, loberman@redhat.com, Jens Axboe , martin.petersen@oracle.com, James.Bottomley@hansenpartnership.com, ming.lei@redhat.com Content-Type: text/plain; charset="UTF-8" List-ID: > -----Original Message----- > From: Artem Bityutskiy [mailto:dedekind1@gmail.com] > Sent: Monday, March 19, 2018 8:12 PM > To: hch@lst.de; Thomas Gleixner > Cc: linux-block@vger.kernel.org; snitzer@redhat.com; hare@suse.de; > mroos@linux.ee; linux-scsi@vger.kernel.org; don.brace@microsemi.com; > pbonzini@redhat.com; loberman@redhat.com; > kashyap.desai@broadcom.com; Jens Axboe; martin.petersen@oracle.com; > James.Bottomley@HansenPartnership.com; ming.lei@redhat.com > Subject: Re: [PATCH V5 1/5] scsi: hpsa: fix selection of reply queue > > On Mon, 2018-03-19 at 08:31 -0600, Jens Axboe wrote: > > I'm assuming that Martin will eventually queue this up. But probably > > for 4.17, then we can always flag it for a backport to stable once > > it's been thoroughly tested. > > Jens, thanks for reply. > > I wonder if folks agree that in this case we should revert > > 84676c1f21e8 genirq/affinity: assign vectors to all possible CPUs > > for v4.16. > > If this was a minor niche use-case regression the -stable scenario would > probably be OK. But the patch seem to miss the fact that kernel's > "possible > CPUs" notion may be way off and side effects are bad. Also it is performance issue as posted at below link, if we just use "84676c1f21e8 genirq/affinity: assign vectors to all possible CPUs". https://www.spinics.net/lists/linux-scsi/msg118301.html Performance drop was resolved using patch set (available at below link)under discussion posted by Ming. https://marc.info/?l=linux-block&m=152050646332092&w=2 Kashyap > > Christoph, Thomas, what do you think? > > Thanks, > Artem.