From: Brian Pane
Date: Sat, 25 May 2002 06:58:39 +0000 (+0000)
Subject: Added EnableMMAP to performance tuning guide
X-Git-Tag: 2.0.37~269
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e30dc76250165a5959c9e70854cd26235693cb5f;p=apache
Added EnableMMAP to performance tuning guide
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95279 13f79535-47bb-0310-9956-ffa450edef68
---
diff --git a/docs/manual/misc/perf-tuning.html b/docs/manual/misc/perf-tuning.html
index 6e0aea4da3..a22a41b9cc 100644
--- a/docs/manual/misc/perf-tuning.html
+++ b/docs/manual/misc/perf-tuning.html
@@ -69,6 +69,8 @@
HostnameLookups
EnableMMAP
+ KeepAliveTimeout
MaxSpareServers
@@ -281,6 +283,35 @@ DirectoryIndex index.cgi index.pl index.shtml index.html
determined by reading this single file, rather than having to
scan the directory for files.
+ Memory-mapping
+
+ In situations where Apache 2.0 needs to look at the contents
+ of a file being delivered--for example, when doing server-side-include
+ processing--it normally memory-maps the file if the OS supports
+ some form of mmap(2).
+
+
+ On some platforms, this memory-mapping improves performance.
+ However, there are cases where memory-mapping can hurt the performance
+ or even the stability of the httpd:
+
+
+ - On some operating systems, mmap does not scale as well as
+ read(2) when the number of CPUs increases. On multiprocessor
+ Solaris servers, for example, Apache 2.0 sometimes delivers
+ server-parsed files faster when mmap is disabled.
+
+ - If you memory-map a file located on an NFS-mounted filesystem
+ and a process on another NFS client machine deletes or truncates
+ the file, your process may get a bus error the next time it tries
+ to access the mapped file content.
+
+
+ For installations where either of these factors applies, you
+ should use EnableMMAP off
to disable the memory-mapping
+ of delivered files. (Note: This directive can be overridden on
+ a per-directory basis.)
+
Process Creation
Prior to Apache 1.3 the MinSpareServers
,