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Groups > linux.kernel > #1360723
| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 2/3] x86/topology: Fix AMD core count |
| Date | 2016-03-18 16:10 +0100 |
| Message-ID | <re4ci-8fa-19@gated-at.bofh.it> (permalink) |
| References | <re4ci-8fa-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
It turns out AMD gets x86_max_cores wrong when there are compute
units.
The issue is that Linux assumes:
nr_logical_cpus = nr_cores * nr_siblings
But AMD reports its CU unit as 2 cores, but then sets num_smp_siblings
to 2 as well.
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andreas Herrmann <aherrmann@suse.com>
Reported-by: Xiong Zhou <jencce.kernel@gmail.com>
Fixes: 1f12e32f4cd5 ("x86/topology: Create logical package id")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160317095220.GO6344@twins.programming.kicks-ass.net
---
arch/x86/kernel/cpu/amd.c | 8 ++++----
arch/x86/kernel/smpboot.c | 11 ++++++-----
2 files changed, 10 insertions(+), 9 deletions(-)
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -313,9 +313,9 @@ static void amd_get_topology(struct cpui
node_id = ecx & 7;
/* get compute unit information */
- smp_num_siblings = ((ebx >> 8) & 3) + 1;
+ cores_per_cu = smp_num_siblings = ((ebx >> 8) & 3) + 1;
+ c->x86_max_cores /= smp_num_siblings;
c->compute_unit_id = ebx & 0xff;
- cores_per_cu += ((ebx >> 8) & 3);
} else if (cpu_has(c, X86_FEATURE_NODEID_MSR)) {
u64 value;
@@ -331,8 +331,8 @@ static void amd_get_topology(struct cpui
u32 cus_per_node;
set_cpu_cap(c, X86_FEATURE_AMD_DCM);
- cores_per_node = c->x86_max_cores / nodes_per_socket;
- cus_per_node = cores_per_node / cores_per_cu;
+ cus_per_node = c->x86_max_cores / nodes_per_socket;
+ cores_per_node = cus_per_node * cores_per_cu;
/* store NodeID, use llc_shared_map to store sibling info */
per_cpu(cpu_llc_id, cpu) = node_id;
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[PATCH 2/3] x86/topology: Fix AMD core count Peter Zijlstra <peterz@infradead.org> - 2016-03-18 16:10 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Borislav Petkov <bp@alien8.de> - 2016-03-18 17:50 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Borislav Petkov <bp@alien8.de> - 2016-03-21 09:30 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Borislav Petkov <bp@alien8.de> - 2016-03-21 09:30 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Borislav Petkov <bp@alien8.de> - 2016-03-21 11:30 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Peter Zijlstra <peterz@infradead.org> - 2016-03-21 09:30 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Borislav Petkov <bp@alien8.de> - 2016-03-21 15:00 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Borislav Petkov <bp@alien8.de> - 2016-03-22 12:30 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Thomas Gleixner <tglx@linutronix.de> - 2016-03-21 10:00 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Thomas Gleixner <tglx@linutronix.de> - 2016-03-19 10:30 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Borislav Petkov <bp@alien8.de> - 2016-03-19 17:00 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Peter Zijlstra <peterz@infradead.org> - 2016-03-20 11:50 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Borislav Petkov <bp@alien8.de> - 2016-03-20 12:10 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Peter Zijlstra <peterz@infradead.org> - 2016-03-20 13:40 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Peter Zijlstra <peterz@infradead.org> - 2016-03-20 13:50 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Borislav Petkov <bp@alien8.de> - 2016-03-20 14:10 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Peter Zijlstra <peterz@infradead.org> - 2016-03-20 18:20 +0100
Re: [PATCH 2/3] x86/topology: Fix AMD core count Borislav Petkov <bp@alien8.de> - 2016-03-20 19:50 +0100
[tip:x86/urgent] perf/x86/amd: Cleanup Fam10h NB event constraints tip-bot for Peter Zijlstra <tipbot@zytor.com> - 2016-03-29 11:00 +0200
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