Messages in this thread |  | | Date | Tue, 10 Oct 2000 11:28:49 +0200 | From | Jamie Lokier <> | Subject | Re: {PATCH] Re: wasting time on page fault |
| |
Andi Kleen wrote: > > 1. Move the error_code block from divide_error to page_fault; > > this removes one jump from the page_fault path. > > It is not clear that it is worth it. You want to align error_code and > page_fault to 16 or 32 bytes bytes at least, and it would need to execute > some nops depending on the length for fallthrough > The jmp may be actually faster.
The assembler doesn't use nops for alignment -- it inserts longer instructions that are effectively nops, either 1 or two. For larger stretches, the assembler inserts a jmp itself for alignment.
Regardless, I'd expect the page_fault path to occur far more often than any of the other fault/exception handlers that lead to error_code. So much more that not aligning error_code is probably the right thing to do.
-- Jamie - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
|  |