Fix the heuristics for L3 cache size for Arm64 #71029
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Tagging subscribers to this area: @dotnet/gc Issue DetailsWhile L3 cache size is undetermined on Arm64 machines, if we don't get it, use a fixed heuristics based upon the core count.
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| #ifdef _SC_LEVEL1_DCACHE_SIZE | ||
| cacheSize = std::max(cacheSize, ( size_t) sysconf(_SC_LEVEL1_DCACHE_SIZE)); | ||
| size = ( size_t) sysconf(_SC_LEVEL1_DCACHE_SIZE); |
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Q (also applies to the old src) - what does sysconf return if there's no cache of that level? I presume it returns 0, not -1 (the doc says it returns -1 if there's an error).
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@dotnet/jit-contrib , @davidwrighton , @jkotas |
| @@ -876,21 +876,29 @@ bool ReadMemoryValueFromFile(const char* filename, uint64_t* val) | |||
| return result; | |||
| } | |||
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| #define UPDATE_CACHE_SIZE_AND_LEVEL(CACHE_LEVEL) if (size > cacheSize) { cacheSize = size; cacheLevel = CACHE_LEVEL; } | |||
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One last nit - please feel free to do that later if you want to get this in before today's snap for preview 6.
Looking at the usages of this macro, I have realized it would be great to make the size a parameter of the macro too. From the usage sites, it is not obvious where it gets the size from (I have to read the macro definition to figure it out).
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Sure, will do it in follow-up PR
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Linux/arm64 improvements:
windows/arm64 improvements: |
ghost
locked as resolved and limited conversation to collaborators
While L3 cache size is undetermined on Arm64 machines, if we don't get it, use a fixed heuristics based upon the core count.
This led to removing the obscure heuristics we have currently that just multiplies the cache size by 3.