Re: [PATCH v3 05/10] powerpc/smp: Dont assume l2-cache to be superset of sibling
From: Gautham R Shenoy <hidden>
Date: 2020-07-24 07:11:29
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On Thu, Jul 23, 2020 at 02:21:11PM +0530, Srikar Dronamraju wrote:
Current code assumes that cpumask of cpus sharing a l2-cache mask will always be a superset of cpu_sibling_mask. Lets stop that assumption. cpu_l2_cache_mask is a superset of cpu_sibling_mask if and only if shared_caches is set. Cc: linuxppc-dev <redacted> Cc: LKML <redacted> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Anton Blanchard <redacted> Cc: Oliver O'Halloran <oohall@gmail.com> Cc: Nathan Lynch <redacted> Cc: Michael Neuling <redacted> Cc: Gautham R Shenoy <redacted> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Valentin Schneider <redacted> Cc: Jordan Niethe <redacted> Signed-off-by: Srikar Dronamraju <redacted>
Reviewed-by: Gautham R. Shenoy <redacted>
quoted hunk ↗ jump to hunk
--- Changelog v1 -> v2: Set cpumask after verifying l2-cache. (Gautham) arch/powerpc/kernel/smp.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-)diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index da27f6909be1..d997c7411664 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c@@ -1194,6 +1194,7 @@ static bool update_mask_by_l2(int cpu, struct cpumask *(*mask_fn)(int)) if (!l2_cache) return false; + cpumask_set_cpu(cpu, mask_fn(cpu)); for_each_cpu(i, cpu_online_mask) { /* * when updating the marks the current CPU has not been marked@@ -1276,29 +1277,30 @@ static void add_cpu_to_masks(int cpu) * add it to it's own thread sibling mask. */ cpumask_set_cpu(cpu, cpu_sibling_mask(cpu)); + cpumask_set_cpu(cpu, cpu_core_mask(cpu)); for (i = first_thread; i < first_thread + threads_per_core; i++) if (cpu_online(i)) set_cpus_related(i, cpu, cpu_sibling_mask); add_cpu_to_smallcore_masks(cpu); - /* - * Copy the thread sibling mask into the cache sibling mask - * and mark any CPUs that share an L2 with this CPU. - */ - for_each_cpu(i, cpu_sibling_mask(cpu)) - set_cpus_related(cpu, i, cpu_l2_cache_mask); update_mask_by_l2(cpu, cpu_l2_cache_mask); - /* - * Copy the cache sibling mask into core sibling mask and mark - * any CPUs on the same chip as this CPU. - */ - for_each_cpu(i, cpu_l2_cache_mask(cpu)) - set_cpus_related(cpu, i, cpu_core_mask); + if (pkg_id == -1) { + struct cpumask *(*mask)(int) = cpu_sibling_mask; + + /* + * Copy the sibling mask into core sibling mask and + * mark any CPUs on the same chip as this CPU. + */ + if (shared_caches) + mask = cpu_l2_cache_mask; + + for_each_cpu(i, mask(cpu)) + set_cpus_related(cpu, i, cpu_core_mask); - if (pkg_id == -1) return; + } for_each_cpu(i, cpu_online_mask) if (get_physical_package_id(i) == pkg_id)-- 2.18.2