From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from [95.166.99.235] ([95.166.99.235]:47121 "EHLO kernel.dk" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1757979AbZKDTWZ (ORCPT ); Wed, 4 Nov 2009 14:22:25 -0500 Date: Wed, 4 Nov 2009 20:22:30 +0100 From: Jens Axboe Subject: Re: Add extra_buff_count flag Message-ID: <20091104192230.GI8742@kernel.dk> References: <66dfd3fe0911031633s5bef0621g99b4164c2dd174d9@mail.gmail.com> <20091104073525.GQ8742@kernel.dk> <66dfd3fe0911040912s377b8b0eqb81fa3cad3db2d2f@mail.gmail.com> <20091104172932.GD8742@kernel.dk> <66dfd3fe0911040939w7629a514l393e3a6360430b54@mail.gmail.com> <20091104174123.GG8742@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091104174123.GG8742@kernel.dk> Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: Radha Ramachandran Cc: fio@vger.kernel.org On Wed, Nov 04 2009, Jens Axboe wrote: > On Wed, Nov 04 2009, Radha Ramachandran wrote: > > I would rather document it than add it by default in case it starts > > hitting memory constraints because its allocating more memory buffers. > > Yes I agree, I usually don't like having one option implying changes for > another either. So the problem with documentation is that usually nobody reads it. This is what the HOWTO/man page currently has: verify_async=int Fio will normally verify IO inline from the submitting thread. This option takes an integer describing how many async offload threads to create for IO verification instead, causing fio to offload the duty of verifying IO contents to one or more separate threads. If using this offload option, even sync IO engines can benefit from using an iodepth setting higher than 1, as it allows them to have IO in flight while verifies are running. It's already documented... -- Jens Axboe