HL1 & HL2 Booster Library

[BehaartesEtwas]

there is very little difference between a syscall and a context switch performed by the scheduler. to either you have 100% cpu load or you have context switches. if you do noop etc. you won't have control when the kernel takes the cpu away from you. so doing some controlled sleep is actually better, because you give the kernel the time it wants when you don't do anything but can have full cpu when you need it (sched_fifo with a high priority gives you the cpu without interruption long enough to render a frame but not to play a war).
as I wrote, the precision of kernel sleeps is sufficient on appropriate kernels. but if you want to improve it, why don't you sleep a little shorter than required and do the rest of the waiting using rdtsc? i.e. sleep only 900us and busy wait 100us. that could help maybe...

replacing expensive APIs might help of course. but I wouldn't see every syscall as a deprecated API, virtually every low level function has to be run at the kernel - and that is not a problem. usleep and gettimeofday are certainly not deprecated. and tampering with gettimeofday can be dangerous because it affects our instrument to measure the quality (almost) *only* (i.e. the stats command). it will not improve the quality if we save a call that takes 0.05us one or two times per 1000us (i.e. frame).