Call for performance evaluation: net.isr.direct (fwd)

[Andrew Gallatin]

Poul-Henning Kamp writes:
 > The best compromise solution therefore is to change the scheduler
 > to make decisions based on the TSC ticks (or equivalent on other
 > archs) and at regular intervals figure out how fast the CPU ran in
 > the last period and convert the TSC ticks accumulated to a time
 > unit suitable for resource accounting.
 > 
 > 
 > The bad solution is to try to do timekeeping based on hardware
 > counters which are unsuitable for the purpose, the TSC being
 > the primary suspect here, and we will not do that.

I'll bet that nobody will want to touch the scheduler, so we'll
continue be stuck with inflated context switch times on SMP because we
use such an expensive time source.

What if somebody were to port the linux TSC syncing code, and use it
to decide whether or not set kern.timecounter.smp_tsc=1?  Would you
object to that?

Drew