From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752921Ab1GLKD4 (ORCPT ); Tue, 12 Jul 2011 06:03:56 -0400 Received: from 8bytes.org ([88.198.83.132]:45286 "EHLO 8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752723Ab1GLKDz (ORCPT ); Tue, 12 Jul 2011 06:03:55 -0400 Date: Tue, 12 Jul 2011 12:03:54 +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: <20110712100354.GC29812@8bytes.org> References: <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> <20110712094822.GB29812@8bytes.org> <4E1C1A0D.8000707@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4E1C1A0D.8000707@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 12:55:25PM +0300, Avi Kivity wrote: > Have a helper kernel thread do it for you. Or extend use_mm() to return > the old mm (without dropping its refcount) and add a way to restore it. Making use_mm usable for regular tasks too sounds like a good idea. Thanks. > Regarding LWP - I thought the intent was self-profiling by the process > for jits and the like? If you also use it for perf, won't it be > unusable for that? Also, can't the process interfere, from userspace, > by executing the unprivileged LWP instructions? Ingo made perf-integration a merge-requirement for LWP. It is not really well-suited for being integrated into perf because the design goal was easy and efficient self-profiling of tasks (like you stated). So integrating it into perf causes some pain. But lets see how it works out. Joerg