From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id F15DE6B0085 for ; Thu, 2 Dec 2010 06:04:31 -0500 (EST) Date: Thu, 2 Dec 2010 12:04:04 +0100 From: Johannes Weiner Subject: Re: [PATCH 2/7] mm: vmscan: Convert lumpy_mode into a bitmask Message-ID: <20101202110404.GW15564@cmpxchg.org> References: <1290440635-30071-1-git-send-email-mel@csn.ul.ie> <1290440635-30071-3-git-send-email-mel@csn.ul.ie> <20101201102732.GK15564@cmpxchg.org> <20101201105029.GL13268@csn.ul.ie> <20101201112116.GR15564@cmpxchg.org> <20101201115633.GO13268@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101201115633.GO13268@csn.ul.ie> Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: Andrea Arcangeli , KOSAKI Motohiro , Andrew Morton , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Wed, Dec 01, 2010 at 11:56:33AM +0000, Mel Gorman wrote: > On Wed, Dec 01, 2010 at 12:21:16PM +0100, Johannes Weiner wrote: > > On Wed, Dec 01, 2010 at 10:50:29AM +0000, Mel Gorman wrote: > > > On Wed, Dec 01, 2010 at 11:27:32AM +0100, Johannes Weiner wrote: > > > > On Mon, Nov 22, 2010 at 03:43:50PM +0000, Mel Gorman wrote: > > > > > + * lumpy_mode determines how the inactive list is shrunk > > > > > + * LUMPY_MODE_SINGLE: Reclaim only order-0 pages > > > > > + * LUMPY_MODE_ASYNC: Do not block > > > > > + * LUMPY_MODE_SYNC: Allow blocking e.g. call wait_on_page_writeback > > > > > + * LUMPY_MODE_CONTIGRECLAIM: For high-order allocations, take a reference > > > > > + * page from the LRU and reclaim all pages within a > > > > > + * naturally aligned range > > > > > > > > I find those names terribly undescriptive. It also strikes me as an > > > > odd set of flags. Can't this be represented with less? > > > > > > > > LUMPY_MODE_ENABLED > > > > LUMPY_MODE_SYNC > > > > > > > > or, after the rename, > > > > > > > > RECLAIM_MODE_HIGHER = 1 > > > > RECLAIM_MODE_SYNC = 2 > > > > RECLAIM_MODE_LUMPY = 4 > > > > > > My problem with that is you have to infer what the behaviour is from what the > > > flags "are not" as opposed to what they are. For example, !LUMPY_MODE_SYNC > > > implies LUMPY_MODE_ASYNC instead of specifying LUMPY_MODE_ASYNC. > > > > Sounds like a boolean value to me. And it shows: you never actually > > check for RECLAIM_MODE_ASYNC in the code, you just always set it to > > the opposite of RECLAIM_MODE_SYNC - the flag which is actually read. > > If you insist, the ASYNC flag can be dropped. I found it easier to flag > what behaviour was expected than infer it. It seems to be a matter of taste and nobody else seems to care, so I am not insisting. Let's just keep it as it is. -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org