Date: Mon, 27 Oct 2008 11:58:30 -0700 From: Chuck Swiger <cswiger@mac.com> To: =?ISO-8859-1?Q?Francis_Dub=E9?= <freebsd@optiksecurite.com> Cc: freebsd-questions@freebsd.org Subject: Re: collecting pv entries -- suggest increasing PMAP_SHPGPERPROC Message-ID: <E0956D53-6EA3-4E70-91B2-6606EA48869A@mac.com> In-Reply-To: <49060AE0.3000301@optiksecurite.com> References: <49060AE0.3000301@optiksecurite.com>
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On Oct 27, 2008, at 11:39 AM, Francis Dub=E9 wrote: > I've read that this is mainly caused by Apache spawning too many =20 > processes. Everyone seems to suggest to decrease the MaxClients =20 > directive in Apache(set to 450 at the moment), but here's the =20 > problem...i need to increase it ! During peaks all the processes are =20= > in use, we even have little drops sometime because there isn't =20 > enough processes to serve the requests. Our traffic is increasing =20 > slowly over time so i'm affraid that it'll become a real problem =20 > soon. Any tips on how I could deal with this situation, Apache's or =20= > FreBSD's side ? You need to keep your MaxClients setting limited to what your system =20 can run under high load; generally the amount of system memory is the =20= governing factor. [1] If you set your MaxClients higher than that, =20 your system will start swapping under the load and once you start =20 hitting VM, it's game over: your throughput will plummet and clients =20 will start getting lots of broken connections, just as you describe. For a rough starting point, divide system RAM by httpd's typical =20 resident memory size. If your load legitimately exceeds this, you'll =20= need to beef up the machine or run multiple webserver boxes behind a =20 load-balancer (IPFW round-robin or similar with PF is a starting =20 point, but something like a Netscaler or Foundry ServerIron are what =20 the big websites generally use). --=20 -Chuck [1]: There can be other bottlenecks; sometimes poorly written external =20= cgi-bin scripts or dynamic content coming from mod_perl, mod_php, etc =20= can demand a lot of CPU or end up blocking on some resource (ie, DB =20 locking) and choking the webserver performance before it runs out of =20 RAM. But you can run a site getting several million hits a day on a =20 Sun E250 with only 1GB of RAM and 2 x ~400MHz CPU. :-)=
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