Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932140AbbGQLqd (ORCPT ); Fri, 17 Jul 2015 07:46:33 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:38252 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752478AbbGQLqb (ORCPT ); Fri, 17 Jul 2015 07:46:31 -0400 Message-ID: <55A8EABE.1060308@huawei.com> Date: Fri, 17 Jul 2015 19:45:02 +0800 From: "Wangnan (F)" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Peter Zijlstra CC: kaixu xia , , , , , , , , , Subject: Re: [RFC PATCH 5/6] bpf: Implement function bpf_read_pmu() that get the selected hardware PMU conuter References: <1437129816-13176-1-git-send-email-xiakaixu@huawei.com> <1437129816-13176-6-git-send-email-xiakaixu@huawei.com> <20150717110541.GJ12596@twins.programming.kicks-ass.net> <55A8E703.70306@huawei.com> <20150717113924.GD19282@twins.programming.kicks-ass.net> In-Reply-To: <20150717113924.GD19282@twins.programming.kicks-ass.net> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.111.66.109] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020204.55A8EACB.0128,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: a3925c7f2c1bba0c9bd32cd3c7daef65 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1659 Lines: 49 On 2015/7/17 19:39, Peter Zijlstra wrote: > On Fri, Jul 17, 2015 at 07:29:07PM +0800, Wangnan (F) wrote: >> >> On 2015/7/17 19:05, Peter Zijlstra wrote: >>> On Fri, Jul 17, 2015 at 06:43:35PM +0800, kaixu xia wrote: >>>> The function bpf_read_pmu() can get the specific map key, convert >>>> the corresponding map value to the pointer to struct perf_event and >>>> return the Hardware PMU counter value. >>> Thanks for having me on Cc :/ >>> >>>> Signed-off-by: kaixu xia >>>> --- >>>> +static u64 bpf_read_pmu(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) >>>> +{ >>>> + void *value = (void *) (unsigned long) r1; >>>> + struct perf_event *event; >>>> + u64 count; >>>> + >>>> + if (!value || !(*(unsigned long *)value)) >>>> + return 0; >>>> + >>>> + event = (struct perf_event *)(*(unsigned long *)value); >>>> + >>>> + if (event->state == PERF_EVENT_STATE_ACTIVE) >>>> + event->pmu->read(event); >>>> + >>>> + count = local64_read(&event->count); >>>> + >>>> + return count; >>>> +} >>> Hell no, that's way broken. >> What about calling perf_event_read_value() then? > Depends on what all you need, if you need full perf events to work then > yes perf_event_read_value() is your only option. > > But note that that requires scheduling, so you cannot actually use it > for tracing purposes etc.. What you mean "full perf events"? Even with your code some event still not work? Thank you. -- 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/