powerpc/smp: Check for duplicate topologies and consolidate (375370a1) · Commits · 戴 / test

CACHE and COREGROUP domains are now part of default topology. However on systems that don't support CACHE or COREGROUP, these domains will eventually be degenerated. The degeneration happens per CPU. Do note the current fixup_topology() logic ensures that mask of a domain that is not supported on the current platform is set to the previous domain. Instead of waiting for the scheduler to degenerated try to consolidate based on their masks and sd_flags. This is done just before setting the scheduler topology. Signed-off-by:

Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by:

Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200921095653.9701-9-srikar@linux.vnet.ibm.com

arch/powerpc/kernel/smp.c

+26 −0

Original line number	Diff line number	Diff line
		@@ -1401,6 +1401,8 @@ int setup_profiling_timer(unsigned int multiplier)

		static void fixup_topology(void)
		{
		int i;

		#ifdef CONFIG_SCHED_SMT
		if (has_big_cores) {
		pr_info("Big cores detected but using small core scheduling\n");
		@@ -1410,6 +1412,30 @@ static void fixup_topology(void)

		if (!has_coregroup_support())
		powerpc_topology[mc_idx].mask = powerpc_topology[cache_idx].mask;

		/*
		* Try to consolidate topology levels here instead of
		* allowing scheduler to degenerate.
		* - Dont consolidate if masks are different.
		* - Dont consolidate if sd_flags exists and are different.
		*/
		for (i = 1; i <= die_idx; i++) {
		if (powerpc_topology[i].mask != powerpc_topology[i - 1].mask)
		continue;

		if (powerpc_topology[i].sd_flags && powerpc_topology[i - 1].sd_flags &&
		powerpc_topology[i].sd_flags != powerpc_topology[i - 1].sd_flags)
		continue;

		if (!powerpc_topology[i - 1].sd_flags)
		powerpc_topology[i - 1].sd_flags = powerpc_topology[i].sd_flags;

		powerpc_topology[i].mask = powerpc_topology[i + 1].mask;
		powerpc_topology[i].sd_flags = powerpc_topology[i + 1].sd_flags;
		#ifdef CONFIG_SCHED_DEBUG
		powerpc_topology[i].name = powerpc_topology[i + 1].name;
		#endif
		}
		}

		void __init smp_cpus_done(unsigned int max_cpus)

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