Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761684Ab2KAOc5 (ORCPT ); Thu, 1 Nov 2012 10:32:57 -0400 Received: from a193-30.smtp-out.amazonses.com ([199.255.193.30]:19254 "EHLO a193-30.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761656Ab2KAOcv (ORCPT ); Thu, 1 Nov 2012 10:32:51 -0400 Date: Thu, 1 Nov 2012 14:32:49 +0000 From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Shan Wei cc: paulmck@linux.vnet.ibm.com, dipankar@in.ibm.com, Kernel-Maillist Subject: Re: [PATCH 7/9] rcu: use this_cpu_ptr per-cpu helper instead of per_cpu_ptr(p, raw_smp_processor_id()) In-Reply-To: <50923C2F.6060200@gmail.com> Message-ID: <0000013abc638281-aaf452ca-0b94-4d56-8b8d-6b2b0c683668-000000@email.amazonses.com> References: <50910A17.1090600@gmail.com> <0000013ab7eefc03-20a4ba94-f83f-4624-9dac-dfe3924277b4-000000@email.amazonses.com> <20121031200842.GC3027@linux.vnet.ibm.com> <50923C2F.6060200@gmail.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: 199.255.193.30 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 667 Lines: 18 On Thu, 1 Nov 2012, Shan Wei wrote: > Paul E. McKenney said, at 2012/11/1 4:08: > > > > One thing to keep in mind -- the only purpose of this is to diffuse > > memory contention. So there is no need to disable preemption. > > same question to me. > Christoph, maybe __this_cpu_read is a better choice which don't disable preemption. Correct. Use __this_cpu_read to reduce overhead on processor that require emulation. -- 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/