Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754372AbbGQLaq (ORCPT ); Fri, 17 Jul 2015 07:30:46 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:45659 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750699AbbGQLan (ORCPT ); Fri, 17 Jul 2015 07:30:43 -0400 Message-ID: <55A8E703.70306@huawei.com> Date: Fri, 17 Jul 2015 19:29:07 +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 , kaixu xia CC: , , , , , , , , 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> In-Reply-To: <20150717110541.GJ12596@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 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1480 Lines: 53 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? ... struct perf_event_context *ctx; u64 enabled, u64 running ctx = perf_event_ctx_lock(event); if (!event->state == PERF_EVENT_STATE_ERROR) { count = perf_event_read_value(event, &enable, &running); } perf_event_ctx_unlock(event, ctx); ... Code is from perf_read(). 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/