From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752596Ab1GLJsY (ORCPT ); Tue, 12 Jul 2011 05:48:24 -0400 Received: from 8bytes.org ([88.198.83.132]:38675 "EHLO 8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750808Ab1GLJsX (ORCPT ); Tue, 12 Jul 2011 05:48:23 -0400 Date: Tue, 12 Jul 2011 11:48:22 +0200 From: Joerg Roedel To: Avi Kivity Cc: Peter Zijlstra , Will Deacon , Frederic Weisbecker , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , Ingo Molnar , "acme@ghostprotocols.net" , Jason Wessel Subject: Re: [PATCH 1/3] perf: add context field to perf_event Message-ID: <20110712094822.GB29812@8bytes.org> References: <4E1BF5A1.5070301@redhat.com> <1310459898.18678.108.camel@twins> <4E1C0F02.9040906@redhat.com> <1310462046.14978.11.camel@twins> <4E1C10F8.6010300@redhat.com> <1310462335.14978.12.camel@twins> <4E1C1373.5080500@redhat.com> <1310463060.14978.17.camel@twins> <20110712094131.GA29812@8bytes.org> <4E1C1771.9010300@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4E1C1771.9010300@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 12, 2011 at 12:44:17PM +0300, Avi Kivity wrote: > On 07/12/2011 12:41 PM, Joerg Roedel wrote: >> > Using TIF_bits sounds like a much better solution for this, wakeups are >> > really rather expensive and its best to avoid extra if at all possible. >> >> I would rather vote for Avi's solution too. Such a functionality is very >> helpful for LWP-perf integration as well (because we need a way to call >> do_mmap for a task != current). >> > > It's not needed for that. See use_mm() (caller must be a kernel thread). But in our case the caller would be the process that wants to count, not a kernel thread. Joerg