At 02:48 PM 11/15/2010, John wrote:
> Page fault latency wouldn't really cause huge delays at all from
an application
If you're referring to what I said about log writes, this doesn't
relate to page faults. Log lines simply have to be written to disk,
and when the OS determines that it shouldn't (or can't) cache these
writes and return immediately, it becomes a blocking operation,
leading to reduced server performance. I've run extensive tests on
this and discussed the situation with Valve.
That is very debatable. I have a hard time believing that writing
tiny files affects 'performance', and I emphasized that word because
I have no idea what baseline performance is in the context of a game
server. Writing anything to disk from cache takes a hit anyways, ie:
TLB hits/misses, etc.
> You're always going to have jitter from syscalls, and syscalls
are exactly what is used to generate what 'FPS' says..
Syscall latency is generally not enough to make a server drop from
150 to 100 FPS, as in your initial example. If it does, there's a
serious OS-side performance issue.
Do you know where the 'FPS' gets it's number from?
> The point I am trying to make here is that with all the info you
provided above, it's still speculation.
By asking that the FPS number be removed from "stats" output, you
seem to be indicating that it is not a valid measure of performance.
I don't believe that is the case.
Again, that is debatable. For too long there have been many many
people (including myself at one point) that claim/claimed high FPS
was great and did this and that. Well, after reverse engineering, I
have come to the conclusion that FPS only drives the engines time for
things like snaps (not sure what the term is for VALVe games, snaps
are quake 3 terms) and a few other things..
I guess all and all, people only complain about the FPS of a server
because they don't realize most things in a game are estimated due to
general relativity, interpolation/exterp, prediction, etc.
-M
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