Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751532Ab3JTSIr (ORCPT ); Sun, 20 Oct 2013 14:08:47 -0400 Received: from a10-51.smtp-out.amazonses.com ([54.240.10.51]:59430 "EHLO a10-51.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750949Ab3JTSIq (ORCPT ); Sun, 20 Oct 2013 14:08:46 -0400 Date: Sun, 20 Oct 2013 18:08:44 +0000 From: Christoph Lameter X-X-Sender: cl@gentwo.org To: JoonSoo Kim cc: Joonsoo Kim , Pekka Enberg , Andrew Morton , David Rientjes , Linux Memory Management List , LKML , Wanpeng Li Subject: Re: [PATCH v2 3/5] slab: restrict the number of objects in a slab In-Reply-To: Message-ID: <00000141d70e0e22-bd66f3af-822a-47dd-bbd9-fe68ad8da2ff-000000@email.amazonses.com> References: <1381989797-29269-1-git-send-email-iamjoonsoo.kim@lge.com> <1381989797-29269-4-git-send-email-iamjoonsoo.kim@lge.com> <00000141c7cb668b-1e2528ea-ce87-4380-a0dd-e5be9384cd84-000000@email.amazonses.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-SES-Outgoing: 2013.10.20-54.240.10.51 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1158 Lines: 27 On Sat, 19 Oct 2013, JoonSoo Kim wrote: > > Ok so that results in a mininum size object size of 2^(12 - 8) = 2^4 == > > 16 bytes on x86. This is not true for order 1 pages (which SLAB also > > supports) where we need 32 bytes. > > According to current slab size calculating logic, slab whose object size is > less or equal to 16 bytes use only order 0 page. So there is no problem. Ok then lets add a VM_BUG_ON to detect the situation when someone tries something different. > > Problems may arise on PPC or IA64 where the page size may be larger than > > 64K. With 64K we have a mininum size of 2^(16 - 8) = 256 bytes. For those > > arches we may need 16 bit sized indexes. Maybe make that compile time > > determined base on page size? > 64KByte results in 16 bit sized indexes? > > Okay. I will try it. Again compile time. You had runtime in some earlier patches which adds new branches to key functions. -- 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/