Hi all, has anyone tested latency on a P4 machine with Hyperthreading support? (HT simulates two processors on one processor using - I guess - the spare time available in the cpu when it is waiting for, for example, memory accesses).
Anyway, on a: P4 2.4G 800MHz fsb, 875P chipset, 1G ram, Seagate Barracuda V 60G drive: Booting into an smp kernel with HT enabled in the bios (kernel based on 2.4.21-rc6 with the usual low latency, preemptive and full acpi kernel patches) I see both processors, but the latency in the disk tests (using latencytest 0.42) has spikes that go up to 10/15 msecs, specially in the read/write test. If I boot into a up kernel, or if I boot with acpi=off I see only one processor and the latency for the disk tests is fine. Same kernel, same alsa on a dual Athlon MP 1800+ machine does not show any abnormal latency behavior so this seems to be confined to HT machines... :-( I guess "made up" processors are not as good as real ones :-) -- Fernando