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Date: Mon, 22 Jul 2013 18:48:57 -0400 From: Rik van Riel <riel@...hat.com> To: Johannes Weiner <hannes@...xchg.org> CC: Andrew Morton <akpm@...ux-foundation.org>, Mel Gorman <mgorman@...e.de>, Andrea Arcangeli <aarcange@...hat.com>, linux-mm@...ck.org, linux-kernel@...r.kernel.org Subject: Re: [patch 3/3] mm: page_alloc: fair zone allocator policy On 07/22/2013 05:04 PM, Johannes Weiner wrote: > On Mon, Jul 22, 2013 at 04:21:07PM -0400, Rik van Riel wrote: >> On 07/19/2013 04:55 PM, Johannes Weiner wrote: >> >>> @@ -1984,7 +1992,8 @@ this_zone_full: >>> goto zonelist_scan; >>> } >>> >>> - if (page) >>> + if (page) { >>> + atomic_sub(1U << order, &zone->alloc_batch); >>> /* >>> * page->pfmemalloc is set when ALLOC_NO_WATERMARKS was >>> * necessary to allocate the page. The expectation is >> >> Could this be moved into the slow path in buffered_rmqueue and >> rmqueue_bulk, or would the effect of ignoring the pcp buffers be >> too detrimental to keeping the balance between zones? > > What I'm worried about is not the inaccury that comes from the buffer > size but the fact that there are no guaranteed buffer empty+refill > cycles. The reclaimer could end up feeding the pcp list that the > allocator is using indefinitely, which brings us back to the original > problem. If you have >= NR_CPU jobs running, the kswapds are bound to > share CPUs with the allocating tasks, so the scenario is not unlikely. You are absolutely right. Thinking about it some more, I cannot think of a better way to do this than your patch. Reviewed-by: Rik van Riel <riel@...hat.com> -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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