From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f54.google.com (mail-pb0-f54.google.com [209.85.160.54]) (using TLSv1 with cipher RC4-MD5 (128/128 bits)) (No client certificate requested) by mail09.linbit.com (LINBIT Mail Daemon) with ESMTPS id 34D65100008C for ; Thu, 24 May 2012 18:19:20 +0200 (CEST) Received: by mail-pb0-f54.google.com with SMTP id ro2so605089pbb.27 for ; Thu, 24 May 2012 09:19:19 -0700 (PDT) Sender: Tejun Heo Date: Thu, 24 May 2012 09:19:14 -0700 From: Tejun Heo To: Kent Overstreet Message-ID: <20120524161914.GD27983@google.com> References: <1337817771-25038-1-git-send-email-koverstreet@google.com> <1337817771-25038-2-git-send-email-koverstreet@google.com> <20120524160944.GB27983@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120524160944.GB27983@google.com> Cc: axboe@kernel.dk, yehuda@hq.newdream.net, dm-devel@redhat.com, neilb@suse.de, linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org, mpatocka@redhat.com, vgoyal@redhat.com, bharrosh@panasas.com, linux-fsdevel@vger.kernel.org, sage@newdream.net, agk@redhat.com, drbd-dev@lists.linbit.com Subject: Re: [Drbd-dev] [PATCH v2 01/14] block: Generalized bio pool freeing List-Id: Coordination of development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, May 24, 2012 at 09:09:44AM -0700, Tejun Heo wrote: > On Wed, May 23, 2012 at 05:02:38PM -0700, Kent Overstreet wrote: > > With the old code, when you allocate a bio from a bio pool you have to > > implement your own destructor that knows how to find the bio pool the > > bio was originally allocated from. > > > > This adds a new field to struct bio (bi_pool) and changes > > bio_alloc_bioset() to use it. This makes various bio destructors > > unnecessary, so they're then deleted. > > > > Signed-off-by: Kent Overstreet > > Change-Id: I5eb66c1d6910757f4af8755b8857dcbe4619cf8d > > Please drop Change-ID tag and it would be great how you tested the > changes, other than that, > > Acked-by: Tejun Heo To add a bit here too. Please explain "why" you're making this change. Is it because bi_destructor interface is cumbersome? Adding bi_pool is overhead - why is it justified? Is it because one pointer is fine to add to struct bio (which I kinda agree) or are there future changes which will reverse the overhead (which is the case here). In general, I find the descriptions insufficient. They don't describe the reasons and reasoning behind the patch. Thanks. -- tejun