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From: Mel Gorman <mel@csn.ul.ie>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>,
	Linux Memory Management List <linux-mm@kvack.org>,
	Christoph Lameter <cl@linux-foundation.org>,
	Nick Piggin <npiggin@suse.de>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Lin Ming <ming.m.lin@intel.com>,
	Zhang Yanmin <yanmin_zhang@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Pekka Enberg <penberg@cs.helsinki.fi>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 18/22] Use allocation flags as an index to the zone watermark
Date: Thu, 23 Apr 2009 11:03:48 +0100	[thread overview]
Message-ID: <20090423100348.GA26953@csn.ul.ie> (raw)
In-Reply-To: <20090423092350.F6E6.A69D9226@jp.fujitsu.com>

On Thu, Apr 23, 2009 at 09:27:15AM +0900, KOSAKI Motohiro wrote:
> > On Wed, 2009-04-22 at 18:14 +0100, Mel Gorman wrote:
> > > Preference of taste really. When I started a conversion to accessors, it
> > > changed something recognised to something new that looked uglier to me.
> > > Only one place cares about the union enough to access is via an array so
> > > why spread it everywhere.
> > 
> > Personally, I'd say for consistency.  Someone looking at both forms
> > wouldn't necessarily know that they refer to the same variables unless
> > they know about the union.
> 
> for just clalification...
> 
> AFAIK, C language specification don't gurantee point same value.
> compiler can insert pad between struct-member and member, but not insert
> into array.
> 

Considering that they are the same type for elements and arrays, I
didn't think padding would ever be a problem.

> However, all gcc version don't do that. I think. but perhaps I missed
> some minor gcc release..
> 
> So, I also like Dave's idea. but it only personal feeling.
> 

The tide is against me on this one :).

How about I roll a patch on top of this set that replaces the union by
calling all sites? I figure that patch will go through a few revisions before
people are happy with the final API. However, as the patch wouldn't change
functionality, I'd like to see this series getting wider testing if possible. The
replace-union-with-single-array patch can be easily folded in then when
it settles.

Sound like a plan?

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab

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  reply	other threads:[~2009-04-23 10:03 UTC|newest]

Thread overview: 93+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-22 13:53 [PATCH 00/22] Cleanup and optimise the page allocator V7 Mel Gorman
2009-04-22 13:53 ` [PATCH 01/22] Replace __alloc_pages_internal() with __alloc_pages_nodemask() Mel Gorman
2009-04-22 13:53 ` [PATCH 02/22] Do not sanity check order in the fast path Mel Gorman
2009-04-22 16:13   ` Dave Hansen
2009-04-22 17:11     ` Mel Gorman
2009-04-22 17:30       ` Dave Hansen
2009-04-23  0:13         ` Mel Gorman
2009-04-23  1:34           ` Dave Hansen
2009-04-23  9:58             ` Mel Gorman
2009-04-23 17:36               ` Dave Hansen
2009-04-24  2:57                 ` KOSAKI Motohiro
2009-04-24 10:34                 ` Mel Gorman
2009-04-24 14:16                   ` Dave Hansen
2009-04-23 19:26             ` Dave Hansen
2009-04-23 19:45               ` Dave Hansen
2009-04-24  9:21                 ` Mel Gorman
2009-04-24 14:25                   ` Dave Hansen
2009-04-22 20:11       ` David Rientjes
2009-04-22 20:20         ` Christoph Lameter
2009-04-23  7:44         ` Pekka Enberg
2009-04-23 22:44       ` Andrew Morton
2009-04-22 13:53 ` [PATCH 03/22] Do not check NUMA node ID when the caller knows the node is valid Mel Gorman
2009-04-22 13:53 ` [PATCH 04/22] Check only once if the zonelist is suitable for the allocation Mel Gorman
2009-04-22 13:53 ` [PATCH 05/22] Break up the allocator entry point into fast and slow paths Mel Gorman
2009-04-22 13:53 ` [PATCH 06/22] Move check for disabled anti-fragmentation out of fastpath Mel Gorman
2009-04-22 13:53 ` [PATCH 07/22] Calculate the preferred zone for allocation only once Mel Gorman
2009-04-23 22:48   ` Andrew Morton
2009-04-22 13:53 ` [PATCH 08/22] Calculate the migratetype " Mel Gorman
2009-04-22 13:53 ` [PATCH 09/22] Calculate the alloc_flags " Mel Gorman
2009-04-23 22:52   ` Andrew Morton
2009-04-24 10:47     ` Mel Gorman
2009-04-24 17:51       ` Andrew Morton
2009-04-22 13:53 ` [PATCH 10/22] Remove a branch by assuming __GFP_HIGH == ALLOC_HIGH Mel Gorman
2009-04-22 13:53 ` [PATCH 11/22] Inline __rmqueue_smallest() Mel Gorman
2009-04-22 13:53 ` [PATCH 12/22] Inline buffered_rmqueue() Mel Gorman
2009-04-22 13:53 ` [PATCH 13/22] Inline __rmqueue_fallback() Mel Gorman
2009-04-22 13:53 ` [PATCH 14/22] Do not call get_pageblock_migratetype() more than necessary Mel Gorman
2009-04-22 13:53 ` [PATCH 15/22] Do not disable interrupts in free_page_mlock() Mel Gorman
2009-04-23 22:59   ` Andrew Morton
2009-04-24  0:07     ` KOSAKI Motohiro
2009-04-24  0:33     ` KOSAKI Motohiro
2009-04-24 11:33       ` Mel Gorman
2009-04-24 11:52         ` Lee Schermerhorn
2009-04-24 11:18     ` Mel Gorman
2009-04-22 13:53 ` [PATCH 16/22] Do not setup zonelist cache when there is only one node Mel Gorman
2009-04-22 20:24   ` David Rientjes
2009-04-22 20:32     ` Lee Schermerhorn
2009-04-22 20:34       ` David Rientjes
2009-04-23  0:11         ` KOSAKI Motohiro
2009-04-23  0:19     ` Mel Gorman
2009-04-22 13:53 ` [PATCH 17/22] Do not check for compound pages during the page allocator sanity checks Mel Gorman
2009-04-22 13:53 ` [PATCH 18/22] Use allocation flags as an index to the zone watermark Mel Gorman
2009-04-22 17:11   ` Dave Hansen
2009-04-22 17:14     ` Mel Gorman
2009-04-22 17:47       ` Dave Hansen
2009-04-23  0:27         ` KOSAKI Motohiro
2009-04-23 10:03           ` Mel Gorman [this message]
2009-04-24  6:41             ` KOSAKI Motohiro
2009-04-22 20:06   ` David Rientjes
2009-04-23  0:29     ` Mel Gorman
2009-04-27 17:00     ` [RFC] Replace the watermark-related union in struct zone with a watermark[] array Mel Gorman
2009-04-27 20:48       ` David Rientjes
2009-04-27 20:54         ` Mel Gorman
2009-04-27 20:51           ` Christoph Lameter
2009-04-27 21:04           ` David Rientjes
2009-04-30 13:35             ` Mel Gorman
2009-04-30 13:48               ` Dave Hansen
2009-05-12 14:13                 ` [RFC] Replace the watermark-related union in struct zone with a watermark[] array V2 Mel Gorman
2009-05-12 15:05                   ` [RFC] Replace the watermark-related union in struct zone with awatermark[] " Dave Hansen
2009-05-13  8:31                   ` [RFC] Replace the watermark-related union in struct zone with a watermark[] " KOSAKI Motohiro
2009-04-22 13:53 ` [PATCH 19/22] Update NR_FREE_PAGES only as necessary Mel Gorman
2009-04-23 23:06   ` Andrew Morton
2009-04-23 23:04     ` Christoph Lameter
2009-04-24 13:06     ` Mel Gorman
2009-04-22 13:53 ` [PATCH 20/22] Get the pageblock migratetype without disabling interrupts Mel Gorman
2009-04-22 13:53 ` [PATCH 21/22] Use a pre-calculated value instead of num_online_nodes() in fast paths Mel Gorman
2009-04-22 23:04   ` David Rientjes
2009-04-23  0:44     ` Mel Gorman
2009-04-23 19:29       ` David Rientjes
2009-04-24 13:31         ` [PATCH] Do not override definition of node_set_online() with macro Mel Gorman
2009-04-22 13:53 ` [PATCH 22/22] slab: Use nr_online_nodes to check for a NUMA platform Mel Gorman
2009-04-22 14:37   ` Pekka Enberg
2009-04-27  7:58 ` [PATCH 00/22] Cleanup and optimise the page allocator V7 Zhang, Yanmin
2009-04-27 14:38   ` Mel Gorman
2009-04-28  1:59     ` Zhang, Yanmin
2009-04-28 10:27       ` Mel Gorman
2009-04-28 10:31       ` [PATCH] Properly account for freed pages in free_pages_bulk() and when allocating high-order pages in buffered_rmqueue() Mel Gorman
2009-04-28 16:37         ` Christoph Lameter
2009-04-28 16:51           ` Mel Gorman
2009-04-28 17:15             ` Hugh Dickins
2009-04-28 18:07               ` [PATCH] Properly account for freed pages in free_pages_bulk() and when allocating high-order pages in buffered_rmqueue() V2 Mel Gorman
2009-04-28 18:25                 ` Hugh Dickins
2009-04-28 18:36               ` [PATCH] Properly account for freed pages in free_pages_bulk() and when allocating high-order pages in buffered_rmqueue() Mel Gorman

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