https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106328
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Keywords| |lto
Last reconfirmed| |2022-07-18
Ever confirmed|0 |1
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
That's the WPA LTRANS file generation which does not use the jobserver but
parallelizes for I/O. There is --param lto-max-streaming-parallelism you
can use to limit things but it's default is 32 (but that would be per
actual parallel invoked LTO link step, so with -j8 it's 8 * 32 when there
are 8 parallel invoked link steps).
See gcc/lto/lto.{c,cc}:stream_out_partitions which indeed says
#ifdef HAVE_WORKING_FORK
...
/* Do not run more than LTO_PARALLELISM streamings
FIXME: we ignore limits on jobserver. */
if (lto_parallelism > 0 && nruns >= lto_parallelism)
{
wait_for_child ();
...
if (!cpid)
{
setproctitle ("lto1-wpa-streaming");
so "confirmed" - it doesn't honor the jobserver. Note without using
-flto=auto or -flto=jobserver it would be all serial, note the above
also does not honor a limit placed via -flto=8 I think.
