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SubjectRe: Scheduler regression from caffcdd8d27ba78730d5540396ce72ad022aff2c
On Tue, Jul 22, 2014 at 15:35:14 +0200,
Peter Zijlstra <peterz@infradead.org> wrote:
>On Tue, Jul 22, 2014 at 03:26:03PM +0200, Peter Zijlstra wrote:
>
>Something like so.. anything obviously broken?

Do you want me to test this change instead of, or combined with the other
patch you wanted tested earlier?

>
>---
> arch/x86/kernel/cpu/intel.c | 22 +++++++++++-----------
> arch/x86/kernel/cpu/intel_cacheinfo.c | 12 ++++++++++++
> 2 files changed, 23 insertions(+), 11 deletions(-)
>
>diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
>index 0fd955778f35..9483ee5b3991 100644
>--- a/arch/x86/kernel/cpu/intel.c
>+++ b/arch/x86/kernel/cpu/intel.c
>@@ -370,6 +370,17 @@ static void init_intel(struct cpuinfo_x86 *c)
> */
> detect_extended_topology(c);
>
>+ if (!cpu_has(c, X86_FEATURE_XTOPOLOGY)) {
>+ /*
>+ * let's use the legacy cpuid vector 0x1 and 0x4 for topology
>+ * detection.
>+ */
>+ c->x86_max_cores = intel_num_cpu_cores(c);
>+#ifdef CONFIG_X86_32
>+ detect_ht(c);
>+#endif
>+ }
>+
> l2 = init_intel_cacheinfo(c);
> if (c->cpuid_level > 9) {
> unsigned eax = cpuid_eax(10);
>@@ -438,17 +449,6 @@ static void init_intel(struct cpuinfo_x86 *c)
> set_cpu_cap(c, X86_FEATURE_P3);
> #endif
>
>- if (!cpu_has(c, X86_FEATURE_XTOPOLOGY)) {
>- /*
>- * let's use the legacy cpuid vector 0x1 and 0x4 for topology
>- * detection.
>- */
>- c->x86_max_cores = intel_num_cpu_cores(c);
>-#ifdef CONFIG_X86_32
>- detect_ht(c);
>-#endif
>- }
>-
> /* Work around errata */
> srat_detect_node(c);
>
>diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
>index a952e9c85b6f..9c8f7394c612 100644
>--- a/arch/x86/kernel/cpu/intel_cacheinfo.c
>+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
>@@ -730,6 +730,18 @@ unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c)
> #endif
> }
>
>+#ifdef CONFIG_X86_HT
>+ /*
>+ * If cpu_llc_id is not yet set, this means cpuid_level < 4 which in
>+ * turns means that the only possibility is SMT (as indicated in
>+ * cpuid1). Since cpuid2 doesn't specify shared caches, and we know
>+ * that SMT shares all caches, we can unconditionally set cpu_llc_id to
>+ * c->phys_proc_id.
>+ */
>+ if (per_cpu(cpu_llc_id, cpu) == BAD_APICID)
>+ per_cpu(cpu_llc_id, cpu) = c->phys_proc_id;
>+#endif
>+
> c->x86_cache_size = l3 ? l3 : (l2 ? l2 : (l1i+l1d));
>
> return l2;
>--
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