On 08/02/2017 11:34 PM, Daniel Santos wrote:
> I'm working on a patch to modify the testsuite to obey the
> --load-average value if one is passed to make. It seems to work pretty
> well, except for libstdc++ which doesn't load gcc/libs/gcc-defs.exp
> since it defines it's own ${tool}_functions. I haven't dug too deeply
> into libstdc++'s testsuite yet, but how does it manage parallelization
> if it isn't using the routines in gcc-defs.exp? I'm thinking I will
> need a separate load-limit.exp file or some such.
>
> This feature would be very helpful since you cannot interrupt a test run
> and restart from where you left off. Also, if you suspend the job, then
> you will get timeouts. So it would be helpful to have a way to have it
> yield when you need to do something else on your machine, or if you're
> using a shared test machine and you want to use all available CPU, but
> not crowd out other users.
>
> Due to not having actual interprocess communication, the check_cpu_load
> procedure uses an algo that gives lower numbered jobs slightly more
> priority than higher numbered jobs. When the load average is exceeded,
> the job sleeps an amount of time based upon the "priority" (lower
> numbered jobs sleep less) and a random number - this helps prevent feast
> or famine cycles where all jobs stop when the load is too high and then
> all jobs start again and saturate the CPUs, bouncing back and forth.
>
> gcc/testsuite/ChangeLog
>
> * gcc/Makefile.in (check-parallel-%): Export job number to environment.
> * gcc/testsuite/lib/gcc-defs.exp (num_jobs, load_max, getloadavg_exe):
> New global variables.
> (check_cpu_load): New proc to check speed limit.
> (gcc_parallel_test_run_p): Modify to call check_cpu_load before
> acquiring a new lock file.
So does this perform better than make -j X -l X? I use that with good
success.
jeff
