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From:   Like Xu <like.xu.linux@gmail.com>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Ian Rogers <irogers@google.com>
Cc:     Alexander Antonov <alexander.antonov@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Stephane Eranian <eranian@google.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] perf iostat: Use system-wide mode if the target cpu_list is unspecified
Date:   Mon, 27 Sep 2021 16:11:14 +0800
Message-Id: <20210927081115.39568-1-likexu@tencent.com>
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From: Like Xu <likexu@tencent.com>

An iostate use case like "perf iostat 0000:16,0000:97 -- ls" should be
implemented to work in system-wide mode to ensure that the output from
print_header() is consistent with the user documentation perf-iostat.txt,
rather than incorrectly assuming that the kernel does not support it:

 Error:
 The sys_perf_event_open() syscall returned with 22 (Invalid argument) \
 for event (uncore_iio_0/event=0x83,umask=0x04,ch_mask=0xF,fc_mask=0x07/).
 /bin/dmesg | grep -i perf may provide additional information.

This error is easily fixed by assigning system-wide mode by default
for IOSTAT_RUN only when the target cpu_list is unspecified.

Signed-off-by: Like Xu <likexu@tencent.com>
---
 tools/perf/builtin-stat.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index f6e87b7be5fa..f0ecfda34ece 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -2408,6 +2408,8 @@ int cmd_stat(int argc, const char **argv)
 			goto out;
 		} else if (verbose)
 			iostat_list(evsel_list, &stat_config);
+		if (iostat_mode == IOSTAT_RUN && !target__has_cpu(&target))
+			target.system_wide = true;
 	}
 
 	if (add_default_attributes())
-- 
2.32.0