From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754779Ab3BKJqx (ORCPT ); Mon, 11 Feb 2013 04:46:53 -0500 Received: from e32.co.us.ibm.com ([32.97.110.150]:38693 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753930Ab3BKJqv (ORCPT ); Mon, 11 Feb 2013 04:46:51 -0500 Date: Mon, 11 Feb 2013 15:14:24 +0530 From: Srikar Dronamraju To: Oleg Nesterov Cc: Arnaldo Carvalho de Melo , Ingo Molnar , Peter Zijlstra , Steven Rostedt , Anton Arapov , Frank Eigler , Jiri Olsa , Josh Stone , Masami Hiramatsu , "Suzuki K. Poulose" , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/7] perf: Introduce hw_perf_event->tp_target and ->tp_list Message-ID: <20130211094424.GE525@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20130204190225.GA10840@redhat.com> <20130204190246.GA10865@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20130204190246.GA10865@redhat.com> User-Agent: Mutt/1.5.20 (2009-06-14) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13021109-5406-0000-0000-0000052780C2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Oleg Nesterov [2013-02-04 20:02:46]: > sys_perf_event_open()->perf_init_event(event) is called before > find_get_context(event), this means that event->ctx == NULL when > class->reg(TRACE_REG_PERF_REGISTER/OPEN) is called and thus it > can't know if this event is per-task or system-wide. > > This patch adds hw_perf_event->tp_target for PERF_TYPE_TRACEPOINT, > this is analogous to PERF_TYPE_BREAKPOINT/bp_target we already have. > The patch also moves ->bp_target up so that it can overlap with the > new member, this can help the compiler to generate the better code. > > trace_uprobe_register() will use it for prefiltering to avoid the > unnecessary breakpoints in mm's we do not want to trace. > > ->tp_target doesn't have its own reference, but we can rely on the > fact that either sys_perf_event_open() holds a reference, or it is > equal to event->ctx->task. So this pointer is always valid until > free_event(). > > Also add the "struct list_head tp_list" into this union. It is not > strictly necessary, but it can simplify the next changes and we can > add it for free. > > Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju > --- > include/linux/perf_event.h | 9 +++++++-- > kernel/events/core.c | 5 ++++- > 2 files changed, 11 insertions(+), 3 deletions(-) > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index 6bfb2fa..c9775e9 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -135,16 +135,21 @@ struct hw_perf_event { > struct { /* software */ > struct hrtimer hrtimer; > }; > + struct { /* tracepoint */ > + struct task_struct *tp_target; > + /* for tp_event->class */ > + struct list_head tp_list; > + }; > #ifdef CONFIG_HAVE_HW_BREAKPOINT > struct { /* breakpoint */ > - struct arch_hw_breakpoint info; > - struct list_head bp_list; > /* > * Crufty hack to avoid the chicken and egg > * problem hw_breakpoint has with context > * creation and event initalization. > */ > struct task_struct *bp_target; > + struct arch_hw_breakpoint info; > + struct list_head bp_list; > }; > #endif > }; > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 1b2e516..340fb53 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -6162,11 +6162,14 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, > > if (task) { > event->attach_state = PERF_ATTACH_TASK; > + > + if (attr->type == PERF_TYPE_TRACEPOINT) > + event->hw.tp_target = task; > #ifdef CONFIG_HAVE_HW_BREAKPOINT > /* > * hw_breakpoint is a bit difficult here.. > */ > - if (attr->type == PERF_TYPE_BREAKPOINT) > + else if (attr->type == PERF_TYPE_BREAKPOINT) > event->hw.bp_target = task; > #endif > } > -- > 1.5.5.1 > -- Thanks and Regards Srikar Dronamraju