Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761020Ab3D3Rzp (ORCPT ); Tue, 30 Apr 2013 13:55:45 -0400 Received: from mga09.intel.com ([134.134.136.24]:38071 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760832Ab3D3Rzm (ORCPT ); Tue, 30 Apr 2013 13:55:42 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,582,1363158000"; d="scan'208";a="329068031" Subject: Re: [PATCH 1/2] Make the batch size of the percpu_counter configurable From: Tim Chen To: Christoph Lameter Cc: Andrew Morton , Tejun Heo , Al Viro , Dave Hansen , Andi Kleen , linux-kernel , linux-mm In-Reply-To: <0000013e5c1377c5-49a8fca5-eb04-4e3a-a507-ce3a47fea685-000000@email.amazonses.com> References: <0000013e5b24d2c5-9b899862-e2fd-4413-8094-4f1e5a0c0f62-000000@email.amazonses.com> <1367339009.27102.174.camel@schen9-DESK> <0000013e5bfd1548-a6ef7962-7b00-495b-8e83-d7a08413e165-000000@email.amazonses.com> <1367344094.27102.182.camel@schen9-DESK> <0000013e5c1377c5-49a8fca5-eb04-4e3a-a507-ce3a47fea685-000000@email.amazonses.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 30 Apr 2013 10:55:22 -0700 Message-ID: <1367344522.27102.184.camel@schen9-DESK> Mime-Version: 1.0 X-Mailer: Evolution 2.32.3 (2.32.3-1.fc14) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1117 Lines: 28 On Tue, 2013-04-30 at 17:53 +0000, Christoph Lameter wrote: > On Tue, 30 Apr 2013, Tim Chen wrote: > > > > And why is it a pointer? > > > > A pointer because the default percpu_counter_batch value could change > > later when cpus come online after we initialize per cpu counter and > > percpu_counter_batch will get computed again in percpu_counter_startup. > > Making it a pointer will make it unnecessary to come back and change the > > batch sizes if we use static batch value and default batch size. > > But you will have to dereference the pointer whenever you want the batch > size from the hot path. Looks like it would be better to put the value > there directly. You have a list of percpu counters that can be traversed > to change the batch size. > I have considered that. But the list is not available unless we have CONFIG_HOTPLUG_CPU compiled in. Tim -- 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/