From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from imap.thunk.org ([74.207.234.97]:60578 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752599AbaIBLd2 (ORCPT ); Tue, 2 Sep 2014 07:33:28 -0400 Date: Tue, 2 Sep 2014 07:31:04 -0400 From: "Theodore Ts'o" 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 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 In-Reply-To: <20140902012222.GA21405@infradead.org> Sender: linux-btrfs-owner@vger.kernel.org List-ID: > - 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