Re: Scheduler regression from caffcdd8d27ba78730d5540396ce72ad022aff2c
From: Bruno Wolff III
Date: Tue Jul 22 2014 - 10:11:32 EST
On Tue, Jul 22, 2014 at 15:35:14 +0200,
Peter Zijlstra <peterz@xxxxxxxxxxxxx> 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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