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| <H1 ALIGN="CENTER">Hints on Running a High-Performance Web Server</H1> |
| |
| Running Apache on a heavily loaded web server, one often encounters |
| problems related to the machine and OS configuration. "Heavy" is |
| relative, of course - but if you are seeing more than a couple hits |
| per second on a sustained basis you should consult the pointers on |
| this page. In general the suggestions involve how to tune your kernel |
| for the heavier TCP load, hardware/software conflicts that arise, <EM>etc.</EM> |
| |
| <UL> |
| <LI><A HREF="#AUX">A/UX (Apple's UNIX)</A> |
| <LI><A HREF="#BSD">BSD-based (BSDI, FreeBSD, etc)</A> |
| <LI><A HREF="#DEC">Digital UNIX</A> |
| <LI><A HREF="perf-hp.html">HPUX</A> |
| <LI><A HREF="#Linux">Linux</A> |
| <LI><A HREF="#Solaris">Solaris</A> |
| <LI><A HREF="#SunOS">SunOS 4.x</A> |
| <LI><A HREF="#SVR4">SVR4</A> |
| </UL> |
| |
| <HR> |
| |
| <H3><A NAME="AUX"> |
| A/UX (Apple's UNIX) |
| </A></H3> |
| |
| If you are running Apache on A/UX, a page that gives some helpful |
| performance hints (concerning the <EM>listen()</EM> queue and using |
| virtual hosts) |
| <A HREF="http://www.jaguNET.com/apache.html">can be found here</A> |
| |
| <P><HR> |
| |
| <H3><A NAME="BSD"> |
| BSD-based (BSDI, FreeBSD, etc) |
| </A></H3> |
| |
| <A HREF="perf-bsd44.html#initial">Quick</A> and |
| <A HREF="perf-bsd44.html#detail">detailed</A> |
| performance tuning hints for BSD-derived systems. |
| |
| <P><HR> |
| |
| <H3><A NAME="DEC"> |
| Digital UNIX |
| </A></H3> |
| |
| <UL> |
| <LI><A |
| HREF="http://www.digital.com/info/internet/document/ias/tuning.html" |
| >DIGITAL UNIX Tuning Parameters for Web Servers</A> |
| <LI>We have some <A HREF="perf-dec.html">newsgroup postings</A> on how |
| to tune Digital UNIX 3.2 and 4.0. |
| </UL> |
| |
| <P><HR> |
| |
| <H3><A NAME="Linux"> |
| Linux |
| </A></H3> |
| |
| There are no known problems with heavily loaded systems running Linux |
| kernels 2.0.32 or later. Earlier kernels have some problems, and an |
| upgrade to the latest 2.0.x is a good idea to eliminate various security |
| and denial of service attacks. |
| |
| <P><HR> |
| |
| <H3><A NAME="Solaris"> |
| Solaris 2.4 |
| </A></H3> |
| |
| The Solaris 2.4 TCP implementation has a few inherent limitations that |
| only became apparent under heavy loads. This has been fixed to some |
| extent in 2.5 (and completely revamped in 2.6), but for now consult |
| the following URL for tips on how to expand the capabilities if you |
| are finding slowdowns and lags are hurting performance. |
| |
| <P> |
| |
| Other links: |
| |
| <UL> |
| |
| <LI><A HREF="http://www.sun.com/sun-on-net/performance.html"> |
| World Wide Web Server Performance, |
| <http://www.sun.com/sun-on-net/performance.html></A> |
| <LI><A HREF="http://www.rvs.uni-hannover.de/people/voeckler/tune/EN/tune.html"> |
| Solaris 2.x - tuning your TCP/IP stack</A> contains some good technical |
| information about tuning various Solaris TCP/IP parameters. |
| </UL> |
| |
| <P><HR> |
| |
| <H3><A NAME="SunOS"> |
| SunOS 4.x |
| </A></H3> |
| |
| More information on tuning SOMAXCONN on SunOS can be found at |
| <A HREF="http://www.islandnet.com/~mark/somaxconn.html"> |
| http://www.islandnet.com/~mark/somaxconn.html</A>. |
| |
| <P><HR> |
| |
| <H3><A NAME="SVR4"> |
| SVR4 |
| </A></H3> |
| |
| Some SVR4 versions waste three system calls on every |
| <SAMP>gettimeofday()</SAMP> call. Depending on the syntactic |
| form of the <SAMP>TZ</SAMP> environment variable, these |
| systems have several different algorithms to determine the |
| local time zone (presumably <EM>compatible</EM> with |
| something). The following example uses the central european |
| time zone to demonstrate this: |
| <DL> |
| <DT><STRONG>TZ=:MET</STRONG> |
| <DD>This form delegates the knowledge of the time zone |
| information to an external compiled zoneinfo file |
| (à la BSD).<BR> |
| <STRONG>Caveat:</STRONG> Each time the gettimeofday() |
| function is called, the external zone info is read in |
| again (at least on some SVR4 systems). That results in |
| three wasted system calls with every apache request |
| served.<PRE> |
| open("/usr/lib/locale/TZ/MET", O_RDONLY) = 3 |
| read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 7944) = 778 |
| close(3) = 0</PRE> |
| |
| <DT><STRONG>TZ=MET-1MDT,M3.5.0/02:00:00,M10.5.0/03:00:00</STRONG> |
| <DD>This syntax form (à la SYSV) contains all the |
| knowledge about time zone beginning and ending times in |
| its external representation. It has to be parsed each |
| time it is evaluated, resulting in a slight computing |
| overhead, but it requires no system call. Though the |
| table lookup à la BSD is the more sophisticated |
| technical solution, the bad SVR4 implementation makes |
| this the preferred syntax on systems which otherwise |
| access the external zone info file repeatedly. |
| </DL> |
| You should use the <SAMP>truss</SAMP> utility on a |
| single-process apache server (started with the <SAMP>-X</SAMP> |
| debugging switch) to determine whether your system can profit |
| from the second form of the <SAMP>TZ</SAMP> environment |
| variable. If it does, you could integrate the setting of the |
| preferred <SAMP>TZ</SAMP> syntax into the httpd startup |
| script, which is usually simply a copy of (or symbolic link |
| to) the <SAMP>apachectl</SAMP> utility script, or into the |
| system's <SAMP>/etc/TIMEZONE</SAMP> script. |
| |
| <P><HR> |
| |
| <H3>More welcome!</H3> |
| |
| If you have tips to contribute, send mail to <A |
| HREF="mailto:apache@apache.org">apache@apache.org</A> |
| |
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