Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755348Ab3IYLaq (ORCPT ); Wed, 25 Sep 2013 07:30:46 -0400 Received: from mailout32.mail01.mtsvc.net ([216.70.64.70]:58703 "EHLO n23.mail01.mtsvc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755040Ab3IYLap (ORCPT ); Wed, 25 Sep 2013 07:30:45 -0400 Message-ID: <5242C960.7050506@hurleysoftware.com> Date: Wed, 25 Sep 2013 07:30:40 -0400 From: Peter Hurley User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: Lin Ming CC: Fengguang Wu , Greg KH , LKML , lkp@01.org, Tejun Heo Subject: Re: increased vmap_area_lock contentions on "n_tty: Move buffers into n_tty_data" References: <20130913005133.GA32479@localhost> <20130913010936.GA1291@localhost> <5238767D.1080606@hurleysoftware.com> <20130917232214.GA11390@localhost> <5238F252.5070905@hurleysoftware.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated-User: 990527 peter@hurleysoftware.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 895 Lines: 27 On 09/25/2013 05:04 AM, Lin Ming wrote: > On Wed, Sep 18, 2013 at 8:22 AM, Peter Hurley wrote: > [snip] >> >> Looking over vmalloc.c, the critical section footprint of the vmap_area_lock >> could definitely be reduced (even nearly eliminated), but that's a project >> for >> another day :) > > Hi Peter, > > I also looked over vmallo.c, but didn't find obvious way to reduce the > critical section footprint. > Could you share some hints how to do this? vmap_area_list is an RCU list. get_vmalloc_info() doesn't need to take the vmap_area_lock at all. Look at __purge_vmap_area_lazy() for a howto. Regards, Peter Hurley -- 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/