Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757221Ab2KHWbr (ORCPT ); Thu, 8 Nov 2012 17:31:47 -0500 Received: from mx2.parallels.com ([64.131.90.16]:58940 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756659Ab2KHWbq (ORCPT ); Thu, 8 Nov 2012 17:31:46 -0500 Message-ID: <509C32B4.7050105@parallels.com> Date: Thu, 8 Nov 2012 23:31:16 +0100 From: Glauber Costa User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121016 Thunderbird/16.0.1 MIME-Version: 1.0 To: Andrew Morton CC: Christoph Lameter , , , , Johannes Weiner , Tejun Heo , Michal Hocko , Pekka Enberg , David Rientjes , Pekka Enberg , Suleiman Souhlal Subject: Re: [PATCH v6 25/29] memcg/sl[au]b: shrink dead caches References: <1351771665-11076-1-git-send-email-glommer@parallels.com> <1351771665-11076-26-git-send-email-glommer@parallels.com> <20121105164813.2eba5ecb.akpm@linux-foundation.org> <509A0A04.2030503@parallels.com> <20121106231627.3610c908.akpm@linux-foundation.org> <509A2849.9090509@parallels.com> <20121107144612.e822986f.akpm@linux-foundation.org> <0000013ae1050e6f-7f908e0b-720a-4e68-a275-e5086a4f5c74-000000@email.amazonses.com> <20121108112120.fc964c29.akpm@linux-foundation.org> In-Reply-To: <20121108112120.fc964c29.akpm@linux-foundation.org> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [88.2.50.55] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1841 Lines: 43 On 11/08/2012 08:21 PM, Andrew Morton wrote: > On Thu, 8 Nov 2012 17:15:36 +0000 > Christoph Lameter wrote: > >> On Wed, 7 Nov 2012, Andrew Morton wrote: >> >>> What's up with kmem_cache_shrink? It's global and exported to modules >>> but its only external caller is some weird and hopelessly poorly >>> documented site down in drivers/acpi/osl.c. slab and slob implement >>> kmem_cache_shrink() *only* for acpi! wtf? Let's work out what acpi is >>> trying to actually do there, then do it properly, then killkillkill! >> >> kmem_cache_shrink is also used internally. Its simply releasing unused >> cached objects. > > Only in slub. It could be removed outright from the others and > simplified in slub. > >>> Secondly, as slab and slub (at least) have the ability to shed cached >>> memory, why aren't they hooked into the core cache-shinking machinery. >>> After all, it's called "shrink_slab"! >> >> Because the core cache shrinking needs the slab caches to free up memory >> from inodes and dentries. We could call kmem_cache_shrink at the end of >> the shrink passes in vmscan. The price would be that the caches would have >> to be repopulated when new allocations occur. > > Well, the shrinker shouldn't strips away all the cache. It will perform > a partial trim, the magnitude of which increases with perceived > external memory pressure. > > AFACIT, this is correct and desirable behaviour for shrinking > slab's internal caches. > I believe calling this from shrink_slab() is not a bad idea at all. If you're all in favour, I'll cook a patch for this soon -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/