From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yk0-f173.google.com (mail-yk0-f173.google.com [209.85.160.173]) by kanga.kvack.org (Postfix) with ESMTP id 8006B6B0036 for ; Tue, 2 Sep 2014 07:33:28 -0400 (EDT) Received: by mail-yk0-f173.google.com with SMTP id 20so3964040yks.18 for ; Tue, 02 Sep 2014 04:33:28 -0700 (PDT) Received: from imap.thunk.org (imap.thunk.org. [74.207.234.97]) by mx.google.com with ESMTPS id n43si7023582yhd.108.2014.09.02.04.33.27 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Tue, 02 Sep 2014 04:33:28 -0700 (PDT) Date: Tue, 2 Sep 2014 07:31:04 -0400 From: Theodore Ts'o Subject: Re: ext4 vs btrfs performance on SSD array Message-ID: <20140902113104.GD5049@thunk.org> References: <20140902000822.GA20473@dastard> <20140902012222.GA21405@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140902012222.GA21405@infradead.org> Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Hellwig Cc: Dave Chinner , Nikolai Grigoriev , linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-raid@vger.kernel.org, linux-mm@kvack.org, Jens Axboe > - the very small max readahead size For things like the readahead size, that's probably something that we should autotune, based the time it takes to read N sectors. i.e., start N relatively small, such as 128k, and then bump it up based on how long it takes to do a sequential read of N sectors until it hits a given tunable, which is specified in milliseconds instead of kilobytes. > - replacing cfq with deadline (or noop) Unfortunately, that will break ionice and a number of other things... - Ted -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org