From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 74184C54FCB for ; Sun, 26 Apr 2020 20:00:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5AD952070A for ; Sun, 26 Apr 2020 20:00:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726264AbgDZUAW (ORCPT ); Sun, 26 Apr 2020 16:00:22 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:57658 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726171AbgDZUAW (ORCPT ); Sun, 26 Apr 2020 16:00:22 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: krisman) with ESMTPSA id 8605C2A092E From: Gabriel Krisman Bertazi To: Mike Snitzer Cc: agk@redhat.com, dm-devel@redhat.com, linux-kernel@vger.kernel.org, khazhy@google.com, kernel@collabora.com Subject: Re: [PATCH 0/2] Historical Service Time Path Selector Organization: Collabora References: <20200416211336.2423618-1-krisman@collabora.com> <20200423205947.GA13657@lobo> Date: Sun, 26 Apr 2020 16:00:17 -0400 In-Reply-To: <20200423205947.GA13657@lobo> (Mike Snitzer's message of "Thu, 23 Apr 2020 16:59:47 -0400") Message-ID: <855zdm2f1q.fsf@collabora.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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