FPS Dips

[bigtin]

I'm having some unexplainable FPS dips on my servers once every now and again...

http://fpsmeter.fragaholics.de/p,view;7426.html is an example of it.

Server OS: CentOS 5 32bit
Processor: 2.4 Core2Duo
Ram: 2GB
Game(s): cs: source
Start Up Command: LD_PRELOAD=./libsource.so ./srcds_run -game cstrike -ip 193.33.186.252 -port 27015 -maxplayers 20 -tickrate 100 +fps_max 0 +map de_dust2 +servercfgfile server.cfg +tv_enable 0 +tv_maxclients 15 +tv_port 27020
Admin Mods: mani on the pub server

Running Distant's source lib, vanilla 2.6.28 kernel with bloat removed, 1000Hz, only things on the server are an 18 slot pub and 11 slot match (both 100 tick) and pure-ftpd.

That graph was with idler on both cores, sourcetv was on the match server but I've tried with it off and get the same results. Also tried the kernel with RT patch and same problem. Servers are not set to specific cores.

Has anyone got any ideas on what it might be?

[DiSTANT]

bigtin Wrote:I'm having some unexplainable FPS dips on my servers once every now and again...

http://fpsmeter.fragaholics.de/p,view;7426.html is an example of it.

Server OS: CentOS 5 32bit
Processor: 2.4 Core2Duo
Ram: 2GB
Game(s): cs: source
Start Up Command: LD_PRELOAD=./libsource.so ./srcds_run -game cstrike -ip 193.33.186.252 -port 27015 -maxplayers 20 -tickrate 100 +fps_max 0 +map de_dust2 +servercfgfile server.cfg +tv_enable 0 +tv_maxclients 15 +tv_port 27020
Admin Mods: mani on the pub server

Running Distant's source lib, vanilla 2.6.28 kernel with bloat removed, 1000Hz, only things on the server are an 18 slot pub and 11 slot match (both 100 tick) and pure-ftpd.

That graph was with idler on both cores, sourcetv was on the match server but I've tried with it off and get the same results. Also tried the kernel with RT patch and same problem. Servers are not set to specific cores.

Has anyone got any ideas on what it might be?

The dips are due to scheduling problems. This can be caused by using taskset, too many realtime processes. Running HRG's idler can also cause the dips. Minor jitters around 1000FPS aren't a bad thing, but big dips like the ones in your graph are. My best advice is to let the linux kernel try to schedule its own processes.

Good Luck,
DiSTANT

[BehaartesEtwas]

I think on public servers this is quite normal. If people connect or disconnect you will always get those dips. I have one public and one war server running on the same root with the same settings, the public has similar dips (but the game play feels still ok, it's probably just too rare), while the warserver runs perfect.

[bigtin]

Even with idler off completely I still get the dips and get some jitters too.

http://fpsmeter.fragaholics.de/p,view.html?arg[0]=7490 <-- switched over to match server to avoid any map changes

htop output can be seen here http://img11.imageshack.us/img11/6276/htopa.png

[BehaartesEtwas]

well that looks quite fine... maybe you can eliminate the jitter by changing the clock source (see my howto, playing around section), but I would not spend too much time with that. probably not notable.

[DiSTANT]

bigtin Wrote:Even with idler off completely I still get the dips and get some jitters too.

http://fpsmeter.fragaholics.de/p,view.html?arg[0]=7490 <-- switched over to match server to avoid any map changes

htop output can be seen here http://img11.imageshack.us/img11/6276/htopa.png

HTOP is infamous for causing dips. Make sure you don't run that while you are taking a reading.

[bigtin]

I wasn't, just screendumped it so people could spot any dodgy processes.