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Date: Tue, 16 Oct 2012 15:31:13 +0000 From: Christoph Lameter <cl@...ux.com> To: Glauber Costa <glommer@...allels.com> cc: linux-mm@...ck.org, cgroups@...r.kernel.org, Mel Gorman <mgorman@...e.de>, Tejun Heo <tj@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, Michal Hocko <mhocko@...e.cz>, Johannes Weiner <hannes@...xchg.org>, kamezawa.hiroyu@...fujitsu.com, David Rientjes <rientjes@...gle.com>, Pekka Enberg <penberg@...nel.org>, devel@...nvz.org, linux-kernel@...r.kernel.org, Pekka Enberg <penberg@...helsinki.fi>, Suleiman Souhlal <suleiman@...gle.com> Subject: Re: [PATCH v5 07/14] mm: Allocate kernel pages to the right memcg On Tue, 16 Oct 2012, Glauber Costa wrote: > To avoid adding markers to the page - and a kmem flag that would > necessarily follow, as much as doing page_cgroup lookups for no reason, > whoever is marking its allocations with __GFP_KMEMCG flag is responsible > for telling the page allocator that this is such an allocation at > free_pages() time. This is done by the invocation of > __free_accounted_pages() and free_accounted_pages(). Hmmm... The code paths to free pages are often shared between multiple subsystems. Are you sure that this is actually working and accurately tracks the MEMCG pages? > +/* > + * __free_accounted_pages and free_accounted_pages will free pages allocated > + * with __GFP_KMEMCG. > + * > + * Those pages are accounted to a particular memcg, embedded in the > + * corresponding page_cgroup. To avoid adding a hit in the allocator to search > + * for that information only to find out that it is NULL for users who have no > + * interest in that whatsoever, we provide these functions. > + * > + * The caller knows better which flags it relies on. > + */ > +void __free_accounted_pages(struct page *page, unsigned int order) > +{ > + memcg_kmem_uncharge_page(page, order); > + __free_pages(page, order); > +} If we already are introducing such an API: Could it not be made more general so that it can also be used in the future to communicate other characteristics of a page on free? -- 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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