On 22/10/24 10:57, Saurabh Sengar wrote:
On a x86 system under test with 1780 CPUs, topology_span_sane() takes around 8 seconds cumulatively for all the iterations. It is an expensive operation which does the sanity of non-NUMA topology masks.
CPU topology is not something which changes very frequently hence make this check optional for the systems where the topology is trusted and need faster bootup.
Restrict this to SCHED_DEBUG builds so that this penalty can be avoided for the systems who wants to avoid it.
Fixes: ccf74128d66c ("sched/topology: Assert non-NUMA topology masks don't (partially) overlap") Signed-off-by: Saurabh Sengar ssengar@linux.microsoft.com
Please see: http://lore.kernel.org/r/20241010155111.230674-1-steve.wahl@hpe.com
Also note that most distros ship with CONFIG_SCHED_DEBUG=y, so while I'm not 100% against it this would at the very least need to be gated behind e.g. the sched_verbose cmdline argument to be useful.
But before that I'd like the "just run it once" option to be explored first.