From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4F6F446B8; Thu, 26 Sep 2024 12:52:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727355124; cv=none; b=ota1iIB1LPTukavWaXw7+K3itcqpwJgPFpY0H/IJngZlVbgPJj9dx3glUxdWdzxgHmGS0gxsRzB2MK8gK7hpLMxyghe/7ggBlE1jYYGdmSU63kVYuqGteBfdqMqTrhcLmnAGP3rPcqMk1wQaPcD20iKuKDUnD9UvvrWV2F4oBGQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727355124; c=relaxed/simple; bh=KdrTlAxVPGzgCG2oBMur4u+A3dRAEZXCNNqql/A8E0k=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=M/EP4dIWPWhcAXUOjiCu9tf5XKd7DFvT1aPOJHviiJDoNVEkb/otvfKC0kbECqctoNXWiSIWMH9hTThuCwMhI9bASHBf6EeKDDvx2iYueoxFFfEi4zl2KHIuVxOpdnal/NFqmsc238zS6hFMjP1kesZlSYYUgbYff1zg+verIZY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0AA8CC4CEC5; Thu, 26 Sep 2024 12:51:48 +0000 (UTC) Date: Thu, 26 Sep 2024 08:51:18 -0400 From: Steven Rostedt To: Levi Yun Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, a.p.zijlstra@chello.nl, mingo@elte.hu, mark.rutland@arm.com, james.clark@linaro.org, nd@arm.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Peter Zijlstra , Frederic Weisbecker , Arnaldo Carvalho de Melo , Namhyung Kim Subject: Re: [PATCH v2] trace/trace_event_perf: remove duplicate samples on the first tracepoint event Message-ID: <20240926085118.0a823138@rorschach.local.home> In-Reply-To: <20240913021347.595330-1-yeoreum.yun@arm.com> References: <20240913021347.595330-1-yeoreum.yun@arm.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Can one of the perf folks give me an Ack, and I'll take this through my tree. -- Steve On Fri, 13 Sep 2024 03:13:47 +0100 Levi Yun wrote: > When a tracepoint event is created with attr.freq = 1, > 'hwc->period_left' is not initialized correctly. As a result, > in the perf_swevent_overflow() function, when the first time the event occurs, > it calculates the event overflow and the perf_swevent_set_period() returns 3, > this leads to the event are recorded for three duplicate times. > > Step to reproduce: > 1. Enable the tracepoint event & starting tracing > $ echo 1 > /sys/kernel/tracing/events/module/module_free > $ echo 1 > /sys/kernel/tracing/tracing_on > > 2. Record with perf > $ perf record -a --strict-freq -F 1 -e "module:module_free" > > 3. Trigger module_free event. > $ modprobe -i sunrpc > $ modprobe -r sunrpc > > Result: > - Trace pipe result: > $ cat trace_pipe > modprobe-174509 [003] ..... 6504.868896: module_free: sunrpc > > - perf sample: > modprobe 174509 [003] 6504.868980: module:module_free: sunrpc > modprobe 174509 [003] 6504.868980: module:module_free: sunrpc > modprobe 174509 [003] 6504.868980: module:module_free: sunrpc > > By setting period_left via perf_swevent_set_period() as other sw_event did, > This problem could be solved. > > After patch: > - Trace pipe result: > $ cat trace_pipe > modprobe 1153096 [068] 613468.867774: module:module_free: xfs > > - perf sample > modprobe 1153096 [068] 613468.867794: module:module_free: xfs > > Fixes: bd2b5b12849a ("perf_counter: More aggressive frequency adjustment") > Signed-off-by: Levi Yun > --- > Changes in v2: > - Fix build error. > --- > kernel/trace/trace_event_perf.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c > index 05e791241812..3ff9caa4a71b 100644 > --- a/kernel/trace/trace_event_perf.c > +++ b/kernel/trace/trace_event_perf.c > @@ -352,10 +352,16 @@ void perf_uprobe_destroy(struct perf_event *p_event) > int perf_trace_add(struct perf_event *p_event, int flags) > { > struct trace_event_call *tp_event = p_event->tp_event; > + struct hw_perf_event *hwc = &p_event->hw; > > if (!(flags & PERF_EF_START)) > p_event->hw.state = PERF_HES_STOPPED; > > + if (is_sampling_event(p_event)) { > + hwc->last_period = hwc->sample_period; > + perf_swevent_set_period(p_event); > + } > + > /* > * If TRACE_REG_PERF_ADD returns false; no custom action was performed > * and we need to take the default action of enqueueing our event on > -- > LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}