Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751219Ab2F1EM4 (ORCPT ); Thu, 28 Jun 2012 00:12:56 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:50092 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750744Ab2F1EMz (ORCPT ); Thu, 28 Jun 2012 00:12:55 -0400 MIME-Version: 1.0 In-Reply-To: <87txxwxjmu.fsf@sejong.aot.lge.com> References: <87bok7x0e1.fsf@sejong.aot.lge.com> <87txxwxjmu.fsf@sejong.aot.lge.com> Date: Thu, 28 Jun 2012 12:12:53 +0800 Message-ID: Subject: Re: perf support user-space hw_breakpoint? From: Jovi Zhang To: Namhyung Kim Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1420 Lines: 37 Hi, On Thu, Jun 28, 2012 at 10:20 AM, Namhyung Kim wrote: > On Thu, 28 Jun 2012 09:02:02 +0800, Jovi Zhang wrote: >> On Mon, Jun 25, 2012 at 4:26 PM, Namhyung Kim wrote: >>> BTW, when I perf record on a hwbp, it failed with ENOSPC. >>> I guess it's because each per-task-per-cpu event tried to >>> create an event so it'd get more than supported by h/w. >>> The strace told me that the fifth call to perf_event_open >>> failed on my 6-core machine. >>> >> I have same result as you in my linux box. >> This should be a bug cause by commit d1cb9f(perf target: Add uses_mmap field) >> >> Namhyung, How about below patch? >> > > NAK. This uses_mmap field is needed to setup per-task-per-cpu events for > perf record (mostly). Without it, perf suffered from severe scalability > issues. Maybe we can change it not to create per-task-per-cpu events iff > for hwbp events only, but I'm not sure it's the right thing. > > Thanks, > Namhyung > perf tool create cpumaps and threadmaps for evlist, not for evsel, this means we cannot easily create a dummy cpumaps for hwbp event even when evlist include hwbp type evsel. Any ideas? .jovi -- 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/