Messages in this thread | | | Date | Thu, 5 Apr 2012 19:18:45 +0200 | From | Robert Richter <> | Subject | Re: [PATCH 4/4] perf tools: Use sw counter only if hw pmu is not detected |
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On 05.04.12 10:59:04, David Ahern wrote: > On 4/5/12 10:26 AM, Robert Richter wrote: > > Use cpu-clock-tick sw counter for cpu-cycles only if there is no hw > > pmu available. This is the case if the syscall reports ENOENT. In > > other cases (e.g. invalid attributes) we don't want the sw counter to > > be used. > > Isn't the invalid attributes case handled by the > '} else if (err == EINVAL) {' > case before this switch is done?
Yes, but it does not jump out the code path. It is only doing some diagnostics and retries the syscall with some modified attributes or so.
I had have the case what a syscall failed due to invalid attributes and then the sw counter was setup. I got odd results and I needed some time debugging this to realize what was going on.
-Robert
-- Advanced Micro Devices, Inc. Operating System Research Center
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