At 02:20 AM 9/5/2009, John wrote: > >> You need high res timers (HPET), on a newer kernel (2.6.24) > >> > >> -M > > > >I hated that kernel version. I'm running 2.6.26.5-rt8. And even with hpet > > enabled you still want the higher kernel frequency wouldn't you? > >I think Gary meant that you'd need a 2.6.24 or later kernel. HPET and >hrtimers are a rather new addition to Linux. > >If you run something beyond 2.6.26 or so, make sure to also flag the server >as a "real-time" process to remove the kernel's built-in SCHED_OTHER timer >slack, which defaults to 50 usec and makes the FPS a bit less stable. This >can be done with the "chrt" utility. > >With high resolution timers enabled, your machine doesn't need to run at >1000hz, because processes will be woken up at the right times regardless. In >fact, a lower hz rate like 100 generally works out better; the lower number >leads to less flipping of processes between CPUs, fewer unnecessary context >switches to the kernel, etc. The only real advantage to a high hz might be >in more accurate process accounting. > >In my testing, the "-rt" kernel patchset led to an overall reduction in >performance, due to the additional context switching. YMMV.
AFAIK the scheduler clock uses jiffies, so it's bound by what the clock interrupt is using. Running a HZ of 100 with SCHED_FIFO makes it perform worse when looking at tasks to process than a HZ of 1000 because of jiffies being tied into sched_clock. _______________________________________________ To unsubscribe, edit your list preferences, or view the list archives, please visit: http://list.valvesoftware.com/mailman/listinfo/hlds_linux
