From a3515ba0964729c55a5b2bf5c0ae8d2c39eb14be Mon Sep 17 00:00:00 2001
From: Manish Godse <61718172+mangod9@users.noreply.github.com>
Date: Fri, 28 Aug 2020 22:17:01 -0700
Subject: [PATCH] Fix reading cpu cache size for Alpine(musl) (#41532)

* Fix reading cpu cache size for Alpine(musl)

* limiting the fallback to Linux only

* exclude ARM

* fixing copy-paste error
---
 src/coreclr/src/gc/unix/gcenv.unix.cpp   |  9 ++++++++-
 src/coreclr/src/pal/src/misc/sysinfo.cpp | 13 ++++++++++---
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/coreclr/src/gc/unix/gcenv.unix.cpp b/src/coreclr/src/gc/unix/gcenv.unix.cpp
index 8bcc98a..fcba545 100644
--- a/src/coreclr/src/gc/unix/gcenv.unix.cpp
+++ b/src/coreclr/src/gc/unix/gcenv.unix.cpp
@@ -834,9 +834,14 @@ static size_t GetLogicalProcessorCacheSizeFromOS()
     cacheSize = std::max(cacheSize, ( size_t) sysconf(_SC_LEVEL4_CACHE_SIZE));
 #endif
 
-#if defined(HOST_ARM64)
+#if defined(TARGET_LINUX) && !defined(HOST_ARM)
     if (cacheSize == 0)
     {
+        //
+        // Fallback to retrieve cachesize via /sys/.. if sysconf was not available 
+        // for the platform. Currently musl and arm64 should be only cases to use  
+        // this method to determine cache size.
+        // 
         size_t size;
 
         if (ReadMemoryValueFromFile("/sys/devices/system/cpu/cpu0/cache/index0/size", &size))
@@ -850,7 +855,9 @@ static size_t GetLogicalProcessorCacheSizeFromOS()
         if (ReadMemoryValueFromFile("/sys/devices/system/cpu/cpu0/cache/index4/size", &size))
             cacheSize = std::max(cacheSize, size);
     }
+#endif
 
+#if defined(HOST_ARM64)
     if (cacheSize == 0)
     {
         // It is currently expected to be missing cache size info
diff --git a/src/coreclr/src/pal/src/misc/sysinfo.cpp b/src/coreclr/src/pal/src/misc/sysinfo.cpp
index 4592aa2..6b23c17 100644
--- a/src/coreclr/src/pal/src/misc/sysinfo.cpp
+++ b/src/coreclr/src/pal/src/misc/sysinfo.cpp
@@ -565,9 +565,14 @@ PAL_GetLogicalProcessorCacheSizeFromOS()
     cacheSize = std::max(cacheSize, (size_t)sysconf(_SC_LEVEL4_CACHE_SIZE));
 #endif
 
-#if defined(HOST_ARM64)
-    if(cacheSize == 0)
+#if defined(TARGET_LINUX) && !defined(HOST_ARM)
+    if (cacheSize == 0)
     {
+        //
+        // Fallback to retrieve cachesize via /sys/.. if sysconf was not available 
+        // for the platform. Currently musl and arm64 should be only cases to use  
+        // this method to determine cache size.
+        // 
         size_t size;
 
         if(ReadMemoryValueFromFile("/sys/devices/system/cpu/cpu0/cache/index0/size", &size))
@@ -581,8 +586,10 @@ PAL_GetLogicalProcessorCacheSizeFromOS()
         if(ReadMemoryValueFromFile("/sys/devices/system/cpu/cpu0/cache/index4/size", &size))
             cacheSize = std::max(cacheSize, size);
     }
+#endif
 
-    if(cacheSize == 0)
+#if defined(HOST_ARM64)
+    if (cacheSize == 0)
     {
         // It is currently expected to be missing cache size info
         //
-- 
2.7.4