From: David Ahern Date: Thu, 13 Sep 2012 20:59:15 +0000 (-0600) Subject: perf tools: Give user better message if precise is not supported X-Git-Tag: omap-for-v3.8/fixes-for-merge-window-v4-signed~77^2~10^2~7 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2305c82fb35dd2c8c9533303bb1693f1636c66e4;p=pandora-kernel.git perf tools: Give user better message if precise is not supported Platforms (e.g., VM's) without support for precise mode get a confusing error message. e.g., $ perf record -e cycles:p -a -- sleep 1 Error: sys_perf_event_open() syscall returned with 95 (Operation not supported). /bin/dmesg may provide additional information. No hardware sampling interrupt available. No APIC? If so then you can boot the kernel with the "lapic" boot parameter to force-enable it. sleep: Terminated which is not clear that precise mode might be the root problem. With this patch: $ perf record -e cycles:p -fo /tmp/perf.data -- sleep 1 Error: 'precise' request may not be supported. Try removing 'p' modifier sleep: Terminated v2: softened message to 'may not be' supported per Robert's suggestion Signed-off-by: David Ahern Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Robert Richter Link: http://lkml.kernel.org/r/1347569955-54626-4-git-send-email-dsahern@gmail.com Signed-off-by: Arnaldo Carvalho de Melo --- Reading git-diff-tree failed