From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 901D66B01AF for ; Thu, 17 Jun 2010 07:40:02 -0400 (EDT) Subject: Re: [RFC PATCH] mm: let the bdi_writeout fraction respond more quickly From: Richard Kennedy In-Reply-To: <1276714466.1745.625.camel@laptop> References: <1276523894.1980.85.camel@castor.rsk> <1276526681.1980.89.camel@castor.rsk> <1276714466.1745.625.camel@laptop> Content-Type: text/plain; charset="UTF-8" Date: Thu, 17 Jun 2010 12:39:56 +0100 Message-ID: <1276774796.1978.11.camel@castor.rsk> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Peter Zijlstra Cc: Jens Axboe , Andrew Morton , Wu Fengguang , lkml , linux-mm List-ID: On Wed, 2010-06-16 at 20:54 +0200, Peter Zijlstra wrote: > 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). Yep that sounds reasonable. would minimum shift of 4 be ok ? something like max ( (ilog2(dirty_total - 1)- 4) , 4); Unfortunately volunteers don't seem to be leaping out of the woodwork, maybe Andrew could be persuaded to try this in his tree for a while and see if any one squeaks ? regards Richard -- 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