Messages in this thread Patch in this message | | | From | Janakarajan Natarajan <> | Subject | [PATCH 2/2] amd: uncore: Get correct number of cores sharing last level cache | Date | Mon, 5 Jun 2017 11:13:19 -0500 |
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In Family 17h, the number of cores sharing a cache level is obtained from the Cache Properties CPUID leaf (0x8000001d) by passing in the cache level in ECX. In prior families, a cache level of 2 was used to determine this information.
To get the right information, irrespective of Family, iterate over the cache levels using CPUID 0x8000001d. The last level cache is the last value to return a non-zero value in EAX
Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com> --- arch/x86/events/amd/uncore.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c index 8fea711..e5458a9 100644 --- a/arch/x86/events/amd/uncore.c +++ b/arch/x86/events/amd/uncore.c @@ -397,11 +397,25 @@ static int amd_uncore_cpu_starting(unsigned int cpu) if (amd_uncore_llc) { unsigned int apicid = cpu_data(cpu).apicid; - unsigned int nshared; + unsigned int nshared, cache_level = 0, prev_eax = 0; uncore = *per_cpu_ptr(amd_uncore_llc, cpu); - cpuid_count(0x8000001d, 2, &eax, &ebx, &ecx, &edx); - nshared = ((eax >> 14) & 0xfff) + 1; + /* + * Iterate over Cache Topology Definition leaves until no + * more cache descriptions are available + */ + while (1) { + cpuid_count(0x8000001d, cache_level, + &eax, &ebx, &ecx, &edx); + /* + * EAX[0:4] gives type of cache. 0 = No more caches + */ + if ((eax & 0x1f) == 0) + break; + cache_level++; + prev_eax = eax; + } + nshared = ((prev_eax >> 14) & 0xfff) + 1; uncore->id = apicid - (apicid % nshared); uncore = amd_uncore_find_online_sibling(uncore, amd_uncore_llc); -- 1.8.3.1
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