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authorEric Wong <normalperson@yhbt.net>2010-08-30 23:25:59 -0700
committerEric Wong <normalperson@yhbt.net>2010-08-30 23:30:30 -0700
commit2023d725a57b400d8f19a6aad2e7d119ee27d7f3 (patch)
treeae0192878f83d6507efb887da5f2b920ab36e475
parentd634b0699c8eceece5694680be0fc5e731717d92 (diff)
Large buffers can hurt as well as help.  And the difference
in real apps that do a lot of things other than I/O often
makes it not worth it.
(cherry picked from commit f9a7a19a361fd674bab4e2df7e0897015528bba7)
-rw-r--r--TUNING8
1 files changed, 7 insertions, 1 deletions
diff --git a/TUNING b/TUNING
index d96529a..9a54a01 100644
--- a/TUNING
+++ b/TUNING
@@ -22,7 +22,13 @@ See Unicorn::Configurator for details on the config file format.
   listeners under Linux 2.6 because auto-tuning is enabled.  UNIX domain
   sockets do not have auto-tuning buffer sizes; so increasing those will
   allow syscalls and task switches to be saved for larger requests
-  and responses.
+  and responses.  If your app only generates small responses or expects
+  small requests, you may shrink the buffer sizes to save memory, too.
+
+* Having socket buffers too large can also be detrimental or have
+  little effect.  Huge buffers can put more pressure on the allocator
+  and may also thrash CPU caches, cancelling out performance gains
+  one would normally expect.
 
 * Setting "preload_app true" can allow copy-on-write-friendly GC to
   be used to save memory.  It will probably not work out of the box with