Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932628Ab0FPSyg (ORCPT ); Wed, 16 Jun 2010 14:54:36 -0400 Received: from casper.infradead.org ([85.118.1.10]:35137 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932505Ab0FPSyf convert rfc822-to-8bit (ORCPT ); Wed, 16 Jun 2010 14:54:35 -0400 Subject: Re: [RFC PATCH] mm: let the bdi_writeout fraction respond more quickly From: Peter Zijlstra To: Richard Kennedy Cc: Jens Axboe , Andrew Morton , Wu Fengguang , lkml , linux-mm In-Reply-To: <1276526681.1980.89.camel@castor.rsk> References: <1276523894.1980.85.camel@castor.rsk> <1276526681.1980.89.camel@castor.rsk> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Wed, 16 Jun 2010 20:54:26 +0200 Message-ID: <1276714466.1745.625.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1065 Lines: 26 On Mon, 2010-06-14 at 15:44 +0100, Richard Kennedy wrote: > > diff --git a/mm/page-writeback.c b/mm/page-writeback.c > > index 2fdda90..315dd04 100644 > > --- a/mm/page-writeback.c > > +++ b/mm/page-writeback.c > > @@ -144,7 +144,7 @@ static int calc_period_shift(void) > > else > > dirty_total = (vm_dirty_ratio * determine_dirtyable_memory()) / > > 100; > > - return 2 + ilog2(dirty_total - 1); > > + return ilog2(dirty_total - 1) - 4; > > } IIRC I suggested similar things in the past and all we needed to do was find people doing the measurements on different bits of hardware or so.. I don't have any problems with the approach, all we need to make sure is that we never return 0 or a negative number (possibly ensure a minimum positive shift value). -- 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/