Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965265Ab2JXBOM (ORCPT ); Tue, 23 Oct 2012 21:14:12 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:35854 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933806Ab2JXBOK (ORCPT ); Tue, 23 Oct 2012 21:14:10 -0400 Date: Wed, 24 Oct 2012 09:13:56 +0800 From: Shaohua Li To: Rik van Riel Cc: Hugh Dickins , Konstantin Khlebnikov , Minchan Kim , Andrew Morton , Wu Fengguang , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: [PATCH RFC] mm/swap: automatic tuning for swapin readahead Message-ID: <20121024011356.GA6400@kernel.org> References: <506AACAC.2010609@openvz.org> <506DB816.9090107@openvz.org> <20121016005049.GA1467@kernel.org> <20121022073654.GA7821@kernel.org> <20121023055127.GA24239@kernel.org> <50869E6C.1080907@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <50869E6C.1080907@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1007 Lines: 24 On Tue, Oct 23, 2012 at 09:41:00AM -0400, Rik van Riel wrote: > On 10/23/2012 01:51 AM, Shaohua Li wrote: > > >I have no strong point against the global state method. But I'd agree making the > >heuristic simple is preferred currently. I'm happy about the patch if the '+1' > >is removed. > > Without the +1, how will you figure out when to re-enable readahead? Below code in swapin_nr_pages can recover it. + if (offset == prev_offset + 1 || offset == prev_offset - 1) + pages <<= 1; Not perfect, but should work in some sort. This reminds me to think if pagereadahead flag is really required, hit in swap cache is a more reliable way to count readahead hit, and as Hugh mentioned, swap isn't vma bound. Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/