Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934279AbYBHH3q (ORCPT ); Fri, 8 Feb 2008 02:29:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758125AbYBHH3h (ORCPT ); Fri, 8 Feb 2008 02:29:37 -0500 Received: from neuf-infra-smtp-out-sp604003av.neufgp.fr ([84.96.92.124]:46522 "EHLO neuf-infra-smtp-out-sp604003av.neufgp.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758047AbYBHH3g (ORCPT ); Fri, 8 Feb 2008 02:29:36 -0500 Message-ID: <47AC04CD.9090407@cosmosbay.com> Date: Fri, 08 Feb 2008 08:29:17 +0100 From: Eric Dumazet User-Agent: Thunderbird 2.0.0.9 (Windows/20071031) MIME-Version: 1.0 To: Nick Piggin CC: Christoph Lameter , Linus Torvalds , Andrew Morton , LKML , linux-mm@kvack.org Subject: Re: [git pull] more SLUB updates for 2.6.25 References: <200802081812.22513.nickpiggin@yahoo.com.au> In-Reply-To: <200802081812.22513.nickpiggin@yahoo.com.au> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1443 Lines: 35 Nick Piggin a ?crit : > On Friday 08 February 2008 13:13, Christoph Lameter wrote: >> are available in the git repository at: >> >> git://git.kernel.org/pub/scm/linux/kernel/git/christoph/vm.git slub-linus >> >> (includes the cmpxchg_local fastpath since the cmpxchg_local work >> by Matheiu is in now, and the non atomic unlock by Nick. Verified that >> this is not doing any harm after some other patches had been removed. > > Ah, good. I think it is always a good thing to be able to remove atomics. > They place quite a bit of burden on the CPU, especially x86 where it also > has implicit memory ordering semantics (although x86 can speculatively > get around much of the problem, it's obviously worse than no restriction) > > Even if perhaps some cache coherency or timing quirk makes the non-atomic > version slower (all else being equal), then I'd still say that the non > atomic version should be preferred. > What about IRQ masking then ? Many CPU pay high cost for cli/sti pair... And SLAB/SLUB allocators, even if only used from process context, want to disable/re-enable interrupts... I understand kmalloc() want generic pools, but dedicated pools could avoid this cli/sti -- 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/