[PATCH] Count number of logical processors sharing L2 cache

[H.J. Lu]

On Fri, May 13, 2016 at 6:36 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Wed, May 11, 2016 at 1:00 PM, H.J. Lu <hongjiu.lu@intel.com> wrote:
>> Tested on Intel processors with inclusive cache and non-inclusive cache.
>> OK for master?
>>
>>
>> H.J.
>> --
>>         * sysdeps/x86/cacheinfo.c (init_cacheinfo): Check and support
>>         non-inclusive caches on Intel processors.
>> ---
>>  sysdeps/x86/cacheinfo.c | 12 +++++++++++-
>>  1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/sysdeps/x86/cacheinfo.c b/sysdeps/x86/cacheinfo.c
>> index 143b333..8408624 100644
>> --- a/sysdeps/x86/cacheinfo.c
>> +++ b/sysdeps/x86/cacheinfo.c
>> @@ -492,6 +492,9 @@ init_cacheinfo (void)
>>      {
>>        data = handle_intel (_SC_LEVEL1_DCACHE_SIZE, max_cpuid);
>>
>> +      long int core = handle_intel (_SC_LEVEL2_CACHE_SIZE, max_cpuid);
>> +      bool inclusive_cache = true;
>> +
>>        /* Try L3 first.  */
>>        level  = 3;
>>        shared = handle_intel (_SC_LEVEL3_CACHE_SIZE, max_cpuid);
>> @@ -500,7 +503,7 @@ init_cacheinfo (void)
>>         {
>>           /* Try L2 otherwise.  */
>>           level  = 2;
>> -         shared = handle_intel (_SC_LEVEL2_CACHE_SIZE, max_cpuid);
>> +         shared = core;
>>         }
>>
>>        /* Figure out the number of logical threads that share the
>> @@ -526,6 +529,9 @@ init_cacheinfo (void)
>>             }
>>           while (((eax >> 5) & 0x7) != level);
>>
>> +         /* Check if cache is inclusive of lower cache levels.  */
>> +         inclusive_cache = (edx & 0x2) != 0;
>> +
>>           threads = (eax >> 14) & 0x3ff;
>>
>>           /* If max_cpuid >= 11, THREADS is the maximum number of
>> @@ -592,6 +598,10 @@ init_cacheinfo (void)
>>          threads.  */
>>        if (shared > 0 && threads > 0)
>>         shared /= threads;
>> +
>> +      /* Account for non-inclusive L2 and L3 caches.  */
>> +      if (level == 3 && !inclusive_cache)
>> +       shared += core;
>>      }
>>    /* This spells out "AuthenticAMD".  */
>>    else if (is_amd)
>> --
>> 2.5.5
>>
>
> I will check it in today.
>

We need count number of available logical processors sharing L2
cache.


-- 
H.J.
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