On Tue, Mar 14, 2000 at 09:10:33PM +0100, Ingo Molnar wrote:
> ok, i understand. What i find inconsistent is the way we 'punish' the SMP
> kernel with this method. A dual-CPU system would be worse at handling
> latencies than a UP kernel. Yes, two CPUs are less likely to be in a
> latency-critical section at once, but under certain (typical) workloads
> it's going to be pretty often - and nobody is going to care because most
> people will have the nicely preemptable UP kernel. The latency-quality of
> the SMP kernel will be much worse than the UP kernel's latency.
I don't see why. Can you explain?
> our SMP spinlocks are very short and localized now in 90% of the cases,
> basically only maybe some of the filesystem code and fork() is within the
> big kernel lock. But we still do execute in kernel-space without hitting a
> preemption point for many millisecs, and on SMP with lots of RAM the
> probability of having such code paths increases. I just find it hard to
Why ? The length of time between scheduler calls under SMP should be
smaller than the length of time between scheduler calls on UP - no?
-- --------------------------------------------------------- Victor Yodaiken FSMLabs: www.fsmlabs.com www.rtlinux.com- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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