forked from Minki/linux
perf evlist: Fixup brown paper bag on "hint" for --mmap-pages cmdline arg
When failing due to asking for a number of mmap pages that is more than the max, it was suggesting that an even bigger number of mmap pages should be specified, doh, au contraire! Before: [acme@ssdandy linux]$ trace -m 128 usleep 1 Error: Operation not permitted. Hint: Check /proc/sys/kernel/perf_event_mlock_kb (516 kB) setting. Hint: Tried using 516 kB. Hint: Try using a bigger -m/--mmap-pages value. [acme@ssdandy linux]$ After: [acme@ssdandy linux]$ trace -m 128 usleep 1 Error: Operation not permitted. Hint: Check /proc/sys/kernel/perf_event_mlock_kb (516 kB) setting. Hint: Tried using 516 kB. Hint: Try using a smaller -m/--mmap-pages value. [acme@ssdandy linux]$ And to (really) clarify what happens above, when what the user requests is <= max and even then it fails, a changeset is being made to tell that this is a per user limit, not per process (in the above example there was another 'perf trace' running for this user, which was using all the pages it could use). Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Borislav Petkov <bp@suse.de> Cc: David Ahern <dsahern@gmail.com> Cc: Don Zickus <dzickus@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/n/tip-8qope8lxb898narnq5kmu2gf@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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@ -1495,7 +1495,7 @@ int perf_evlist__strerror_mmap(struct perf_evlist *evlist, int err, char *buf, s
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scnprintf(buf, size, "Error:\t%s.\n"
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"Hint:\tCheck /proc/sys/kernel/perf_event_mlock_kb (%d kB) setting.\n"
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"Hint:\tTried using %zd kB.\n"
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"Hint:\tTry using a bigger -m/--mmap-pages value.",
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"Hint:\tTry using a smaller -m/--mmap-pages value.",
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emsg, value, evlist->mmap_len / 1024);
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break;
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default:
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