From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f51.google.com (mail-pa0-f51.google.com [209.85.220.51]) by kanga.kvack.org (Postfix) with ESMTP id E7D3F6B02BE for ; Sun, 20 Oct 2013 14:08:47 -0400 (EDT) Received: by mail-pa0-f51.google.com with SMTP id ld10so3825813pab.10 for ; Sun, 20 Oct 2013 11:08:47 -0700 (PDT) Received: from psmtp.com ([74.125.245.149]) by mx.google.com with SMTP id js8si2358019pbc.134.2013.10.20.11.08.46 for ; Sun, 20 Oct 2013 11:08:47 -0700 (PDT) Date: Sun, 20 Oct 2013 18:08:44 +0000 From: Christoph Lameter 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> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: JoonSoo Kim Cc: Joonsoo Kim , Pekka Enberg , Andrew Morton , David Rientjes , Linux Memory Management List , LKML , Wanpeng Li 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org