Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759309Ab0KRWZ0 (ORCPT ); Thu, 18 Nov 2010 17:25:26 -0500 Received: from mail.windriver.com ([147.11.1.11]:42738 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757554Ab0KRWZZ (ORCPT ); Thu, 18 Nov 2010 17:25:25 -0500 Message-ID: <4CE5A7AE.8070703@windriver.com> Date: Thu, 18 Nov 2010 16:24:46 -0600 From: Jason Wessel User-Agent: Thunderbird 2.0.0.24 (X11/20101027) MIME-Version: 1.0 To: Cyrill Gorcunov CC: Don Zickus , Peter Zijlstra , Ingo Molnar , Robert Richter , ying.huang@intel.com, Andi Kleen , LKML , Frederic Weisbecker Subject: Re: [V2 PATCH 0/6] x86, NMI: give NMI handler a face-lift References: <20101112161144.GP4823@redhat.com> <4CDD6CAD.30303@windriver.com> <20101112172755.GR4823@redhat.com> <20101116184325.GB4823@redhat.com> <4CE2E3C3.6060800@windriver.com> <20101118080516.GJ32621@elte.hu> <4CE52048.5080802@windriver.com> <1290086232.2109.1507.camel@laptop> <20101118193247.GF18100@redhat.com> <20101118215650.GL6028@lenovo> <20101118221554.GA31253@lenovo> In-Reply-To: <20101118221554.GA31253@lenovo> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 18 Nov 2010 22:24:49.0027 (UTC) FILETIME=[69702D30:01CB876F] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2369 Lines: 72 On 11/18/2010 04:15 PM, Cyrill Gorcunov wrote: > On Fri, Nov 19, 2010 at 12:56:50AM +0300, Cyrill Gorcunov wrote: > ... > >> --- >> arch/x86/kernel/cpu/perf_event_p4.c | 21 ++++++++++++--------- >> 1 file changed, 12 insertions(+), 9 deletions(-) >> >> Index: linux-2.6.git/arch/x86/kernel/cpu/perf_event_p4.c >> ===================================================================== >> --- linux-2.6.git.orig/arch/x86/kernel/cpu/perf_event_p4.c >> +++ linux-2.6.git/arch/x86/kernel/cpu/perf_event_p4.c >> @@ -753,19 +753,22 @@ out: >> >> static inline int p4_pmu_clear_cccr_ovf(struct hw_perf_event *hwc) >> { >> - int overflow = 0; >> - u32 low, high; >> + u32 overflow = 0; >> + u32 low, low_cccr, high; >> >> - rdmsr(hwc->config_base + hwc->idx, low, high); >> + /* an official way for overflow indication */ >> + rdmsr(hwc->config_base + hwc->idx, low_cccr, high); >> + overflow |= (low_cccr & P4_CCCR_OVF); >> + >> + /* unflagged overflows */ >> + rdmsr(hwc->event_base + hwc->idx, low, high); >> + overflow |= high & 0x80000000; >> >> - /* we need to check high bit for unflagged overflows */ >> - if ((low & P4_CCCR_OVF) || !(high & (1 << 31))) { >> - overflow = 1; >> + if (overflow) >> > > this should be rather 'if (low_cccr & P4_CCCR_OVF)' otherwise > redundant checking_wrmsrl called, updated patch below > > /me seems should not touch code at all today > --- > > perf, x86: P4 PMU - Fix unflagged overflows handling > > Jason pointed out that kgdb no longer works with new > nmi-watchdog. Don found the reason -- P4 PMU reads CCCR > register instead of counter itself, it forces NMIs to > be eaten by perf subsystem. > > Fix it by reading a proper register. > > v2: Call checking_wrmsrl only if needed > > Reported-by: Jason Wessel > Reported-by: Don Zickus > Signed-off-by: Cyrill Gorcunov > --- > > Jason I've removed your Tested-by because the patch differ a bit > > It is retested and confirmed to work on real HW. This no longer works on qemu/kvm likely because the emulation is incorrect. Thanks, Jason. -- 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/