From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: [PATCH v3 13/16] Make generic_make_request handle arbitrarily large bios Date: Fri, 25 May 2012 17:18:56 -0700 Message-ID: <20120526001856.GA10959@google.com> References: <1337977539-16977-1-git-send-email-koverstreet@google.com> <1337977539-16977-14-git-send-email-koverstreet@google.com> <20120525225852.GG5761@agk-dp.fab.redhat.com> <20120525231232.GH5761@agk-dp.fab.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120525231232.GH5761@agk-dp.fab.redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org, dm-devel@redhat.com, linux-fsdevel@vger.kernel.org, tj@kernel.org, axboe@kernel.dk, agk@redhat.com, neilb@suse.de, drbd-dev@lists.linbit.com, bharrosh@panasas.com, vgoyal@redhat.com, mpatocka@redhat.com, sage@newdream.net, yehuda@hq.newdream.net List-Id: dm-devel.ids On Sat, May 26, 2012 at 12:12:33AM +0100, Alasdair G Kergon wrote: > What I'm trying to say is, by all means, let's continue to clean up this > patch set, but then give it some serious performance testing under > different regimes, compare it against the status quo, do whatever > tuning seems appropriate then let the results guide us. Ok, that is certainly fair. I'm not _terribly_ worried about the performance impact but it's certainly possible performance will require some more work, we do need that testing. What's also going to help with performance is for stacking block devices (and possibly drivers at some point) to be changed to handle arbitrary sized bios, so the splitting code in generic_make_request() can be disabled for them - that should also be pretty easy at this point. I have some other ideas/cleanups that should improve performance too but I'll leave that for later. I really do care deeply about performance - and it's been my experience that really the most important thing for performance is clean, simple code and interfaces - much more than people seem to generally assume, too... From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from zimbra.linbit.com (zimbra.linbit.com [212.69.161.123]) by mail09.linbit.com (LINBIT Mail Daemon) with ESMTP id C9C6E100008C for ; Wed, 30 May 2012 10:40:43 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by zimbra.linbit.com (Postfix) with ESMTP id B2E181B435D for ; Wed, 30 May 2012 10:40:43 +0200 (CEST) Received: from zimbra.linbit.com ([127.0.0.1]) by localhost (zimbra.linbit.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id GRGjXJaIT-qR for ; Wed, 30 May 2012 10:40:43 +0200 (CEST) Received: from soda.linbit (tuerlsteher.linbit.com [86.59.100.100]) by zimbra.linbit.com (Postfix) with ESMTP id 84EC31B435C for ; Wed, 30 May 2012 10:40:43 +0200 (CEST) Resent-Message-ID: <20120530084043.GH4141@soda.linbit> Received: from mail-pz0-f54.google.com (mail-pz0-f54.google.com [209.85.210.54]) (using TLSv1 with cipher RC4-MD5 (128/128 bits)) (No client certificate requested) by mail09.linbit.com (LINBIT Mail Daemon) with ESMTPS id 0ED2E1013804 for ; Sat, 26 May 2012 02:19:01 +0200 (CEST) Received: by dadv36 with SMTP id v36so2438674dad.27 for ; Fri, 25 May 2012 17:19:00 -0700 (PDT) Date: Fri, 25 May 2012 17:18:56 -0700 From: Kent Overstreet To: linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org, dm-devel@redhat.com, linux-fsdevel@vger.kernel.org, tj@kernel.org, axboe@kernel.dk, agk@redhat.com, neilb@suse.de, drbd-dev@lists.linbit.com, bharrosh@panasas.com, vgoyal@redhat.com, mpatocka@redhat.com, sage@newdream.net, yehuda@hq.newdream.net Message-ID: <20120526001856.GA10959@google.com> References: <1337977539-16977-1-git-send-email-koverstreet@google.com> <1337977539-16977-14-git-send-email-koverstreet@google.com> <20120525225852.GG5761@agk-dp.fab.redhat.com> <20120525231232.GH5761@agk-dp.fab.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120525231232.GH5761@agk-dp.fab.redhat.com> Subject: Re: [Drbd-dev] [PATCH v3 13/16] Make generic_make_request handle arbitrarily large bios List-Id: Coordination of development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sat, May 26, 2012 at 12:12:33AM +0100, Alasdair G Kergon wrote: > What I'm trying to say is, by all means, let's continue to clean up this > patch set, but then give it some serious performance testing under > different regimes, compare it against the status quo, do whatever > tuning seems appropriate then let the results guide us. Ok, that is certainly fair. I'm not _terribly_ worried about the performance impact but it's certainly possible performance will require some more work, we do need that testing. What's also going to help with performance is for stacking block devices (and possibly drivers at some point) to be changed to handle arbitrary sized bios, so the splitting code in generic_make_request() can be disabled for them - that should also be pretty easy at this point. I have some other ideas/cleanups that should improve performance too but I'll leave that for later. I really do care deeply about performance - and it's been my experience that really the most important thing for performance is clean, simple code and interfaces - much more than people seem to generally assume, too...