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From: NeilBrown <neilb@suse.de>
To: Mel Gorman <mgorman@suse.de>
Cc: Linux-MM <linux-mm@kvack.org>,
	Linux-Netdev <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	David Miller <davem@davemloft.net>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH 02/13] mm: sl[au]b: Add knowledge of PFMEMALLOC reserve pages
Date: Tue, 26 Apr 2011 21:37:58 +1000	[thread overview]
Message-ID: <20110426213758.450f6f49@notabene.brown> (raw)
In-Reply-To: <1303803414-5937-3-git-send-email-mgorman@suse.de>

On Tue, 26 Apr 2011 08:36:43 +0100 Mel Gorman <mgorman@suse.de> wrote:

> +		/*
> +		 * If there are full empty slabs and we were not forced to
> +		 * allocate a slab, mark this one !pfmemalloc
> +		 */
> +		l3 = cachep->nodelists[numa_mem_id()];
> +		if (!list_empty(&l3->slabs_free) && force_refill) {
> +			struct slab *slabp = virt_to_slab(objp);
> +			slabp->pfmemalloc = false;
> +			clear_obj_pfmemalloc(&objp);
> +			check_ac_pfmemalloc(cachep, ac);
> +			return objp;
> +		}

The comment doesn't match the code.  I think you need to remove the words
"full" and "not" assuming the code is correct which it probably is...

But the code seems to be much more complex than Peter's original, and I don't
see the gain.

Peter's code had only one 'reserved' flag for each kmem_cache.  You seem to
have one for every slab.  I don't see the point.
It is true that yours is in some sense more fair - but I'm not sure the
complexity is worth it.

Was there some particular reason you made the change?

NeilBrown

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  parent reply	other threads:[~2011-04-26 11:38 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-26  7:36 [PATCH 00/13] Swap-over-NBD without deadlocking Mel Gorman
2011-04-26  7:36 ` [PATCH 01/13] mm: Serialize access to min_free_kbytes Mel Gorman
2011-04-26  7:36 ` [PATCH 02/13] mm: sl[au]b: Add knowledge of PFMEMALLOC reserve pages Mel Gorman
2011-04-26 11:15   ` NeilBrown
2011-04-26 11:33     ` Mel Gorman
2011-04-26 12:05       ` NeilBrown
2011-04-26 11:37   ` NeilBrown [this message]
2011-04-26 13:59     ` Mel Gorman
2011-04-27 23:21       ` NeilBrown
2011-04-28  9:46         ` Mel Gorman
2011-04-26  7:36 ` [PATCH 03/13] mm: Introduce __GFP_MEMALLOC to allow access to emergency reserves Mel Gorman
2011-04-26  9:49   ` NeilBrown
2011-04-26 10:36     ` Mel Gorman
2011-04-26 10:53       ` NeilBrown
2011-04-26 14:00         ` Mel Gorman
2011-04-26  7:36 ` [PATCH 04/13] mm: allow PF_MEMALLOC from softirq context Mel Gorman
2011-04-26  7:36 ` [PATCH 05/13] mm: Ignore mempolicies when using ALLOC_NO_WATERMARK Mel Gorman
2011-04-26  7:36 ` [PATCH 06/13] net: Introduce sk_allocation() to allow addition of GFP flags depending on the individual socket Mel Gorman
2011-04-26  7:36 ` [PATCH 07/13] netvm: Allow the use of __GFP_MEMALLOC by specific sockets Mel Gorman
2011-04-26  7:36 ` [PATCH 08/13] netvm: Allow skb allocation to use PFMEMALLOC reserves Mel Gorman
2011-04-26  7:36 ` [PATCH 09/13] netvm: Set PF_MEMALLOC as appropriate during SKB processing Mel Gorman
2011-04-26 12:21   ` NeilBrown
2011-04-26 14:10     ` Mel Gorman
2011-04-26 23:22       ` NeilBrown
2011-04-26  7:36 ` [PATCH 10/13] mm: Micro-optimise slab to avoid a function call Mel Gorman
2011-04-26  7:36 ` [PATCH 11/13] nbd: Set SOCK_MEMALLOC for access to PFMEMALLOC reserves Mel Gorman
2011-04-26  7:36 ` [PATCH 12/13] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage Mel Gorman
2011-04-26 12:30   ` NeilBrown
2011-04-26 14:26     ` Mel Gorman
2011-04-26 23:18       ` NeilBrown
2011-04-27  8:36         ` Mel Gorman
2011-04-26  7:36 ` [PATCH 13/13] mm: Account for the number of times direct reclaimers get throttled Mel Gorman
2011-04-26 12:35   ` NeilBrown
2011-04-26 14:26     ` Mel Gorman
2011-04-26 14:23 ` [PATCH 00/13] Swap-over-NBD without deadlocking Peter Zijlstra
2011-04-26 14:46   ` Mel Gorman
2011-04-26 14:50     ` Peter Zijlstra
2011-04-27  8:43       ` Mel Gorman
2011-04-28 13:31 ` Pavel Machek
2011-04-28 13:42   ` Mel Gorman
  -- strict thread matches above, loose matches on Subject: below --
2011-04-27 16:07 [PATCH 00/13] Swap-over-NBD without deadlocking v3 Mel Gorman
2011-04-27 16:08 ` [PATCH 02/13] mm: sl[au]b: Add knowledge of PFMEMALLOC reserve pages Mel Gorman

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