pipe and af/unix latency differences between aa and jam on smp
Quoted 3 lines
both pipe and afunix should not generate any irq load (other than the IPI with the
reschedule_taskwakeups at least, but they're only dependent on the scheduler
there are some scheduler bits in irqbalance for cpu affinity. irqbalance is in the two jam patchsets with low latency, and not in the patchsets with higher latency.
Signature · 2 lines
Randy Hron http://home.earthlink.net/~rwhron/kernel/bigbox.html
Quoted 7 lines · On Thu, Jul 11, 2002 at 05:02:14AM -0400, [email protected] wrote:
Quoted 3 lines
both pipe and afunix should not generate any irq load (other than the IPI with the
reschedule_taskwakeups at least, but they're only dependent on the schedulerthere are some scheduler bits in irqbalance for cpu affinity. irqbalance is in the two jam patchsets with low latency, and not in the patchsets with higher latency.
I don't see those scheduler bits, it only exports the idle task info so we know if a cpu is idle from irq.
anyways 2.4.19-pre10-jam2 is composed by plain 2.4.19pre10aa2 + a number of patches (including irqbalance,irqrate,smptimers, btw smptimers reintroduces a deadlock crahsing bug exploitable from userspace that I pushed into 2.4 mainline recently). So the difference has to be in the patches into pre10jam2 because pre10aa2 is slow and jam2 is fast. Only looking at the patches it's not clear what can make the difference.
BTW, in your new set of benchmarks rc1aa1 still seems to be compiled in the unfair why that explains the slower I/O results, right? I don't mind of course, just to be sure.
I don't have time to do benchmarks on this myself right now, but if somebody could try to apply the patches in jam2 with a binary search (I'd first suggest to backout irqrate, smptimers and irqbalance and see if it's still fast as I expect), that would be really interesting.
Thanks,
Andrea