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Date:   Sun, 18 Jul 2021 10:37:46 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Yang Jihong <yangjihong1@huawei.com>
Cc:     peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com,
        alexander.shishkin@linux.intel.com, jolsa@redhat.com,
        namhyung@kernel.org, laoar.shao@gmail.com, rostedt@goodmis.org,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf sched: Fix record failed when CONFIG_SCHEDSTATS is
 not set
Message-ID: <YPQuqlhPP/mCKDu3@kernel.org>
References: <20210713112358.194693-1-yangjihong1@huawei.com>
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Em Tue, Jul 13, 2021 at 07:23:58PM +0800, Yang Jihong escreveu:
> The tracepoints trace_sched_stat_{wait, sleep, iowait} are not exposed to user
> if CONFIG_SCHEDSTATS is not set, "perf sched record" records the three events.
> As a result, the command fails to be executed.
> 
> Before:
> 
>   #perf sched record sleep 1
>   event syntax error: 'sched:sched_stat_wait'
>                        \___ unknown tracepoint
> 
>   Error:  File /sys/kernel/tracing/events/sched/sched_stat_wait not found.
>   Hint:   Perhaps this kernel misses some CONFIG_ setting to enable this feature?.
> 
>   Run 'perf list' for a list of valid events
> 
>    Usage: perf record [<options>] [<command>]
>       or: perf record [<options>] -- <command> [<options>]
> 
>       -e, --event <event>   event selector. use 'perf list' to list available events
> 
> Solution:
>   Check whether schedstat tracepoints are exposed. If no, these events are not recorded.

Thanks, applied.

- Arnaldo