From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 06A166B023E for ; Wed, 19 May 2010 17:45:09 -0400 (EDT) Date: Wed, 19 May 2010 23:44:59 +0200 From: Johannes Weiner Subject: Re: [patch 5/5] vmscan: remove may_swap scan control Message-ID: <20100519214459.GD2868@cmpxchg.org> References: <20100430222009.379195565@cmpxchg.org> <20100430224316.198324471@cmpxchg.org> <20100513122935.2161.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100513122935.2161.A69D9226@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: Andrew Morton , Mel Gorman , linux-mm@kvack.org List-ID: On Thu, May 13, 2010 at 12:36:12PM +0900, KOSAKI Motohiro wrote: > > The may_swap scan control flag can be naturally merged into the > > swappiness parameter: swap only if swappiness is non-zero. > > Sorry, NAK. > > AFAIK, swappiness==0 is very widely used in MySQL users community. > They expect this parameter mean "very prefer to discard file cache > rather than swap, but not completely disable swap". > > We shouldn't ignore the real world use case. even if it is a bit strange. Bummer. It's really ugly to have 'zero' mean 'almost nothing'. But since swappiness is passed around as an int, I think we can instead use -1 for 'no swap'. Let me look into it and send a follow-up patch for this as well. Thanks! Hannes -- 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