From: dgaudet Date: Fri, 24 Oct 1997 09:39:17 +0000 (+0000) Subject: document MMAP_SEGMENT_SIZE X-Git-Tag: APACHE_1_3b3~25 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b9d85826cd49887222dbaa5a481c00213fe4c7b2;p=thirdparty%2Fapache%2Fhttpd.git document MMAP_SEGMENT_SIZE git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@79451 13f79535-47bb-0310-9956-ffa450edef68 --- diff --git a/docs/manual/misc/perf-tuning.html b/docs/manual/misc/perf-tuning.html index 16f8c835ef2..98071bce4bf 100644 --- a/docs/manual/misc/perf-tuning.html +++ b/docs/manual/misc/perf-tuning.html @@ -690,17 +690,24 @@ munmap(0x400ee000, 6144) = 0 On some architectures it's slower to mmap small files than it is to simply read them. The define -MMAP_THRESHOLD can be set to the minimum size required before -using mmap. By default it's set to 0 (except on SunOS4 -where experimentation has shown 8192 to be a better value). Using a -tool such as -lmbench -you can determine the optimal setting for your -environment. It may even be the case that mmap isn't used -on your architecture, if so then defining USE_MMAP_FILES +MMAP_THRESHOLD can be set to the minimum +size required before using mmap. By default +it's set to 0 (except on SunOS4 where experimentation has +shown 8192 to be a better value). Using a tool such as lmbench you +can determine the optimal setting for your environment. + +

You may also wish to experiment with MMAP_SEGMENT_SIZE +(default 32768) which determines the maximum number of bytes that +will be written at a time from mmap()d files. Apache only resets the +client's Timeout in between write()s. So setting this +large may lock out low bandwidth clients unless you also increase the +Timeout. + +

It may even be the case that mmap isn't +used on your architecture, if so then defining USE_MMAP_FILES might work (if it works then report back to us). -

Apache does its best to avoid copying bytes around in memory. The first write of any request typically is turned into a writev which combines both the headers and the first hunk of data: