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[87.3.200.174]) by smtp.gmail.com with ESMTPSA id h23-20020a50cdd7000000b004fe924d16cfsm14761513edj.31.2023.03.27.05.37.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 27 Mar 2023 05:37:12 -0700 (PDT) Message-ID: <9a1bb631-587c-9771-99b7-55623c67bb83@redhat.com> Date: Mon, 27 Mar 2023 14:37:11 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: Enable histograms for events/ftrace/timerlat and osnoise Content-Language: en-US From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Masami Hiramatsu , Tom Zanussi , LKML References: In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/24/23 17:13, Daniel Bristot de Oliveira wrote: > Hi Steven > > I would like to collect histograms from timerlat and osnoise tracers event, > but I cannot collect them because they are not tracepoints but... tracer > events. So... > > # ls /sys/kernel/tracing/events/ftrace/timerlat/ > format hist > > no hist, filter, trigger files... Ooop, the hist file exists, what is missing is the trigger file, which is used to enable the histogram... it seems that the "limitation" is around TRACE_EVENT_FL_IGNORE_ENABLE flag, and the fact that ftrace events cannot be enabled/disabled... but wait, as the hist file exist, is there any other way to enable the histogram? (or should we disable hist files for !TRACE_EVENT_FL_IGNORE_ENABLE)? am I missing something? > How hard would it be to enable histograms to the ftrace/osnoise and > ftrace/timerlat events? > > This will allow me to reduce the overhead of rtla timerlat and rtla osnoise > tools... > > Thanks in advance, Stephen! > -- Denny