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 5C6826B0047 for ; Wed, 18 Mar 2009 14:17:21 -0400 (EDT) Date: Wed, 18 Mar 2009 18:17:17 +0000 From: Mel Gorman Subject: Re: [PATCH 24/27] Convert gfp_zone() to use a table of precalculated values Message-ID: <20090318181717.GC24462@csn.ul.ie> References: <1237226020-14057-1-git-send-email-mel@csn.ul.ie> <1237226020-14057-25-git-send-email-mel@csn.ul.ie> <20090318135222.GA4629@csn.ul.ie> <20090318153508.GA24462@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: Linux Memory Management List , Pekka Enberg , Rik van Riel , KOSAKI Motohiro , Johannes Weiner , Nick Piggin , Linux Kernel Mailing List , Lin Ming , Zhang Yanmin , Peter Zijlstra List-ID: On Wed, Mar 18, 2009 at 01:21:30PM -0400, Christoph Lameter wrote: > > > > time. > > > > > > > const int gfp_zone_table[GFP_ZONEMASK] = { > > > > > ZONE_NORMAL, /* 00 No flags set */ > > > > > ZONE_DMA, /* 01 Only GFP_DMA set */ > > > > > ZONE_HIGHMEM, /* 02 Only GFP_HIGHMEM set */ > > > > > ZONE_DMA, /* 03 GFP_HIGHMEM and GFP_DMA set */ > > > > > ZONE_DMA32, /* 04 Only GFP_DMA32 set */ > > > > > ZONE_DMA, /* 05 GFP_DMA and GFP_DMA32 set */ > > > > > ZONE_DMA32, /* 06 GFP_DMA32 and GFP_HIGHMEM set */ > > > > > ZONE_DMA, /* 07 GFP_DMA, GFP_DMA32 and GFP_DMA32 set */ > > > > > ZONE_MOVABLE, /* 08 Only ZONE_MOVABLE set */ > > > > > ZONE_DMA, /* 09 MOVABLE + DMA */ > > > > > ZONE_MOVABLE, /* 0A MOVABLE + HIGHMEM */ > > > > > ZONE_DMA, /* 0B MOVABLE + DMA + HIGHMEM */ > > > > > ZONE_DMA32, /* 0C MOVABLE + DMA32 */ > > > > > ZONE_DMA, /* 0D MOVABLE + DMA + DMA32 */ > > > > > ZONE_DMA32, /* 0E MOVABLE + DMA32 + HIGHMEM */ > > > > > ZONE_DMA /* 0F MOVABLE + DMA32 + HIGHMEM + DMA > > > > > }; > > > > > > > > > > Hmmmm... Guess one would need to add some #ifdeffery here to setup > > > > > ZONE_NORMAL in cases there is no DMA, DMA32 and HIGHMEM. > > > > > > > > > > > > > Indeed, as I said, this is somewhat error prone which is why the patch > > > > calculates the table at run-time instead of compile-time trickery. > > > > > > One would need to define some macros to make it simpler I guess > > > > > > Write something like > > > > > > #ifdef CONFIG_ZONE_DMA > > > #define TZONE_DMA ZONE_DMA > > > #else > > > #define TZONE_DMA ZONE_NORMAL > > > #endif > > > > > > for each configurable item. Then just add the T to the above table. > > > > > > > If you don't mind, I'd like to postpone writing such a patch until a second > > or third pass at improving the allocator. I don't think I'll have the time > > in the short-term to put together a const-initialised-table patch that will > > definitily be correct. > > > > Alternatively, I can drop this patch entirely from the set. > > > > > > Let me give it a shot: > > Note that there is a slight buggyness in the current implementation of > gfp_zone. If you set both GFP_DMA32 and GFP_HIGHMEM and the arch does not > support GFP_DMA32 then gfp_zone returns GFP_HIGHMEM which may result in > memory being allocated that cannot be used for I/O. > > This version here returns GFP_NORMAL which is more correct. > > > #ifdef CONFIG_ZONE_HIGHMEM > #define OPT_ZONE_HIGHMEM ZONE_HIGHMEM > #else > #define OPT_ZONE_HIGHMEM ZONE_NORMAL > #endif > > #ifdef CONFIG_ZONE_DMA > #define OPT_ZONE_DMA ZONE_DMA > #else > #define OPT_ZONE_DMA ZONE_NORMAL > #endif > > #ifdef CONFIG_ZONE_DMA32 > #define OPT_ZONE_DMA32 ZONE_DMA32 > #else > #define OPT_ZONE_DMA32 OPT_ZONE_DMA > #endif > > > const int gfp_zone_table[GFP_ZONEMASK] = { > ZONE_NORMAL, /* 00 No flags set */ > OPT_ZONE_DMA, /* 01 GFP_DMA */ > OPT_ZONE_HIGHMEM, /* 02 GFP_HIGHMEM */ > OPT_ZONE_DMA, /* 03 GFP_HIGHMEM GFP_DMA */ > OPT_ZONE_DMA32, /* 04 GFP_DMA32 */ > OPT_ZONE_DMA, /* 05 GFP_DMA32 GFP_DMA */ > OPT_ZONE_DMA32, /* 06 GFP_DMA32 GFP_HIGHMEM */ > OPT_ZONE_DMA, /* 07 GFP_DMA32 GFP_HIGHMEM GFP_DMA */ > ZONE_NORMAL, /* 08 ZONE_MOVABLE */ > OPT_ZONE_DMA, /* 09 MOVABLE + DMA */ > ZONE_MOVABLE, /* 0A MOVABLE + HIGHMEM */ > OPT_ZONE_DMA, /* 0B MOVABLE + HIGHMEM + DMA */ > OPT_ZONE_DMA32, /* 0C MOVABLE + DMA32 */ > OPT_ZONE_DMA, /* 0D MOVABLE + DMA32 + DMA */ > OPT_ZONE_DMA32, /* 0E MOVABLE + DMA32 + HIGHMEM */ > OPT_ZONE_DMA /* 0F MOVABLE + DMA32 + HIGHMEM + DMA */ > }; > Thanks.At a quick glance, it looks ok but I haven't tested it. As the intention was to get one pass of patches that are not controversial and are "obvious", I have dropped my version of the gfp_zone patch and the subsequent flag cleanup and will revisit it after the first lot of patches has been dealt with. I'm testing again with the remaining patches. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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