[libc-commits] [PATCH] D156566: [libc] Add PAUSE instruction for the RPC spin loop

[Joseph Huber via Phabricator via libc-commits]

jhuber6 created this revision.
jhuber6 added reviewers: jdoerfert, tianshilei1992, JonChesterfield, sivachandra, lntue, michaelrj.
Herald added projects: libc-project, All.
Herald added a subscriber: libc-commits.
jhuber6 requested review of this revision.

The other architectures use a brief sleep to defer work during this spin
loop that checks the RPC mailboxes. This patch adds one for x64 to
improve usage when running the server.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D156566

Files:
  libc/src/__support/RPC/rpc_util.h


Index: libc/src/__support/RPC/rpc_util.h
===================================================================
--- libc/src/__support/RPC/rpc_util.h
+++ libc/src/__support/RPC/rpc_util.h
@@ -12,8 +12,13 @@
 #include "src/__support/CPP/type_traits.h"
 #include "src/__support/GPU/utils.h"
 #include "src/__support/macros/attributes.h"
+#include "src/__support/macros/config.h"
 #include "src/__support/macros/properties/architectures.h"
 
+#ifdef LIBC_TARGET_ARCH_IS_X86
+#include <emmintrin.h>
+#endif
+
 namespace __llvm_libc {
 namespace rpc {
 
@@ -26,6 +31,8 @@
   LIBC_INLINE_ASM("nanosleep.u32 64;" ::: "memory");
 #elif defined(LIBC_TARGET_ARCH_IS_AMDGPU)
   __builtin_amdgcn_s_sleep(2);
+#elif defined(LIBC_TARGET_ARCH_IS_X86)
+  _mm_pause();
 #else
   // Simply do nothing if sleeping isn't supported on this platform.
 #endif


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