[PATCH] D147340: [Support] Improve Windows performance of buffered raw_ostream

[Andrew Ng via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGa3aa916d019c: [Support] Improve Windows performance of buffered raw_ostream (authored by andrewng).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D147340/new/

https://reviews.llvm.org/D147340

Files:
  llvm/lib/Support/raw_ostream.cpp


Index: llvm/lib/Support/raw_ostream.cpp
===================================================================
--- llvm/lib/Support/raw_ostream.cpp
+++ llvm/lib/Support/raw_ostream.cpp
@@ -84,8 +84,15 @@
 }
 
 size_t raw_ostream::preferred_buffer_size() const {
+#ifdef _WIN32
+  // On Windows BUFSIZ is only 512 which results in more calls to write. This
+  // overhead can cause significant performance degradation. Therefore use a
+  // better default.
+  return (16 * 1024);
+#else
   // BUFSIZ is intended to be a reasonable default.
   return BUFSIZ;
+#endif
 }
 
 void raw_ostream::SetBuffered() {


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