Messages in this thread |  | | From | "Albert D. Cahalan" <> | Subject | Re: Context switch times | Date | Fri, 5 Oct 2001 22:24:05 -0400 (EDT) |
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Alan Cox writes: > [somebody]
>> I don't quite agree with you that it doesn't matter. A lot of tests >> (volanomark, other silly things) show that the current scheduler jumps >> processes from CPU to CPU on SMP boxes far too easily
Be careful that your viewer doesn't disturb the system. Please don't even consider using "top" for this.
> #4 On x86 we are horribly cache pessimal. All the task structs are > on the same cache colour. Multiple tasks waiting for the same event > put their variables (like the wait queue) on the same cache line.
If cache problems are bad enough, maybe this pays for itself:
/* old */ current = stack_ptr & ~0x1fff;
/* new */ hash = (stack_ptr>>8)^(stack_ptr>>12)^(stack_ptr>>16)^(stack_ptr>>20); current = (stack_ptr & ~0x1fff) | (hash & 0x1e0);
> The classic example is two steady cpu loads and an occasionally waking > client (like an editor)
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