Messages in this thread |  | | Subject | Re: Using %cr2 to reference "current" | Date | Tue, 6 Nov 2001 10:58:21 +0000 (GMT) | From | Alan Cox <> |
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> Is using %cr2 really faster than the old implementation, or is there > another reason? It seems that the alignment constraints on the stack > still remains, since the %esp solution still remains in places...
The stack is no longer aligned. We allocate two pages and disturb the stack by upto 1.5K. We slab the task structs.
> It might also be worth considering a segment-register based > implementation instead. The reason we're not using %fs and %gs in the > kernel anymore is because of the setup slowness, but perhaps using > them (use %fs since it's much more likely to be NULL and thus faster > to restore) would be faster than using %cr2?
It may be. Likewise its not clear if %cr2 should hold current or a cpu ident pointer (so you dont reload on switch of task). This needs more benchmarking. Its in current -ac to verify the theory is correct not the tuning. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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