From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754781AbcEQIkp (ORCPT ); Tue, 17 May 2016 04:40:45 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:34025 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751153AbcEQIkl (ORCPT ); Tue, 17 May 2016 04:40:41 -0400 Date: Tue, 17 May 2016 10:40:34 +0200 From: Ingo Molnar To: Alexander Shishkin Cc: stable@vger.kernel.org, gregkh@linuxfoundation.org, jolsa@redhat.com, tglx@linutronix.de, torvalds@linux-foundation.org, vincent.weaver@maine.edu, bp@alien8.de, hpa@zytor.com, eranian@google.com, markus.t.metzger@intel.com, acme@redhat.com, linux-kernel@vger.kernel.org, acme@infradead.org, peterz@infradead.org Subject: Re: [tip:perf/urgent] perf/x86/intel/pt: Generate PMI in the STOP region as well Message-ID: <20160517084034.GA12163@gmail.com> References: <1462886313-13660-2-git-send-email-alexander.shishkin@linux.intel.com> <87a8jpta29.fsf@ashishki-desk.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87a8jpta29.fsf@ashishki-desk.ger.corp.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Alexander Shishkin wrote: > tip-bot for Alexander Shishkin writes: > > > Commit-ID: ab92b232ae05c382c3df0e3d6a5c6d16b639ac8c > > Gitweb: http://git.kernel.org/tip/ab92b232ae05c382c3df0e3d6a5c6d16b639ac8c > > Author: Alexander Shishkin > > AuthorDate: Tue, 10 May 2016 16:18:32 +0300 > > Committer: Ingo Molnar > > CommitDate: Thu, 12 May 2016 14:45:59 +0200 > > > > perf/x86/intel/pt: Generate PMI in the STOP region as well > > > > Currently, the PT driver always sets the PMI bit one region (page) before > > the STOP region so that we can wake up the consumer before we run out of > > room in the buffer and have to disable the event. However, we also need > > an interrupt in the last output region, so that we actually get to disable > > the event (if no more room from new data is available at that point), > > otherwise hardware just quietly refuses to start, but the event is > > scheduled in and we end up losing trace data till the event gets removed. > > > > For a cpu-wide event it is even worse since there may not be any > > re-scheduling at all and no chance for the ring buffer code to notice > > that its buffer is filled up and the event needs to be disabled (so that > > the consumer can re-enable it when it finishes reading the data out). In > > other words, all the trace data will be lost after the buffer gets filled > > up. > > > > This patch makes PT also generate a PMI when the last output region is > > full. > > > > Reported-by: Markus Metzger > > Signed-off-by: Alexander Shishkin > > Signed-off-by: Peter Zijlstra (Intel) > > Cc: > > Can we also have this one queued up for stable 4.4 and 4.5? Agreed. Acked-by: Ingo Molnar Thanks, Ingo