[erlang-questions] Fwd: erlang:trace/3 and cpu_timestamp

Lukas Larsson <>
Thu Apr 24 16:17:47 CEST 2014


Hello,

The cpu_timestamp functionality needs the timestamp to be monotonic across
cpus which the linux version of clock_gettime(CLOCK_PROCESS_CPUTIME_ID,_)
isn't. This is why it is disabled on Linux.

Lukas


On Thu, Apr 24, 2014 at 10:56 AM, mats cronqvist <> wrote:

>
>   tracing with high-resolution timers doesn't seem to work un my linux
> boxes (centos6, in this case);
>
> 247> erlang:trace(all,true,[call,cpu_timestamp]).
> ** exception error: bad argument
>      in function  erlang:trace/3
>         called as erlang:trace(all,true,[call,cpu_timestamp])
>
>   Seemingly, this is because this check in aclocal.m4;
>
>    case $host_os in
>        linux*)
>            AC_MSG_RESULT([no; not stable])
>            LIBRT=$xrtlib
>            ;;
>
>   Indeed, commenting out the above and rebuilding beam works;
>
> 1> erlang:trace(all,true,[call,cpu_timestamp]).
> 24
>
>   Is there any reason not to enable this?
>
>   mats
>
>
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