From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gabriel Krisman Bertazi Subject: Re: [PATCH 0/2] Historical Service Time Path Selector Date: Sun, 26 Apr 2020 16:00:17 -0400 Message-ID: <855zdm2f1q.fsf@collabora.com> References: <20200416211336.2423618-1-krisman@collabora.com> <20200423205947.GA13657@lobo> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <20200423205947.GA13657@lobo> (Mike Snitzer's message of "Thu, 23 Apr 2020 16:59:47 -0400") Sender: linux-kernel-owner@vger.kernel.org To: Mike Snitzer Cc: agk@redhat.com, dm-devel@redhat.com, linux-kernel@vger.kernel.org, khazhy@google.com, kernel@collabora.com List-Id: dm-devel.ids Mike Snitzer writes: > > Looks like you've put a lot of time to this and I'd be happy to help > you get this to land upstream. > > But... (you knew there'd be at least one "but" right? ;) I'm not > liking making this path selector request-based specific. All other > selectors up to this point are request-based vs bio-based agnostic. > > Would you be open to dropping patch 1/2 and replacing it with > something like the following patch? > > Then you'd pass 'u64 start_time_ns' into the path_selector_type's > .end_io (and possibly .start_io). I think it is fine. Kind of a MD newbie question, but if I understand correctly, dm_start_time_ns_from_clone is only for bio based multipath, and we just pass req->io_start_time directly on request based multipath, right? If I understand the code correctly, start_io_acct is only called for the bio level DM. I will update the patches, do a quick round of tests with BIO based and send a v2. Thanks a lot, -- Gabriel Krisman Bertazi