[PATCH] D45546: [CachePruning] Clarify the per-directory entry limit on Linux ext4.

[Fangrui Song via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL329966: [CachePruning] Clarify the per-directory entry limit on Linux ext4. (authored by MaskRay, committed by ).

Changed prior to commit:
  https://reviews.llvm.org/D45546?vs=142275&id=142280#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D45546

Files:
  llvm/trunk/include/llvm/Support/CachePruning.h


Index: llvm/trunk/include/llvm/Support/CachePruning.h
===================================================================
--- llvm/trunk/include/llvm/Support/CachePruning.h
+++ llvm/trunk/include/llvm/Support/CachePruning.h
@@ -52,8 +52,11 @@
   /// the number of files based pruning.
   ///
   /// This defaults to 1000000 because with that many files there are
-  /// diminishing returns on the effectiveness of the cache, and file
-  /// systems have a limit on total number of files.
+  /// diminishing returns on the effectiveness of the cache. Some systems have a
+  /// limit on total number of files, and some also limit the number of files
+  /// per directory, such as Linux ext4, with the default setting (block size is
+  /// 4096 and large_dir disabled), there is a per-directory entry limit of
+  /// 508*510*floor(4096/(40+8))~=20M for average filename length of 40.
   uint64_t MaxSizeFiles = 1000000;
 };
 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D45546.142280.patch
Type: text/x-patch
Size: 924 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180412/56fcff4f/attachment.bin>