Messages in this thread | | | Date | Tue, 27 Jul 2004 16:06:17 -0700 | From | Andrew Morton <> | Subject | Re: bh_lru_install |
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"David S. Miller" <davem@redhat.com> wrote: > > So I was doing some profiling of memcpy() calls to try and tune > the UltraSPARC-III memcpy a little more, and you wouldn't believe > what was at the top of the list during a kernel build :-) > > It's bh_lru_install. On a 64-bit system every time the local > cpu's lru->bh[0] doesn't match 'bh' we do a 64-byte memcpy() > from the stack into the lru->bh[] array.
Well I said it was dopey-but-simple ;)
> It shouldn't be too hard to make the code just work without > an on-stack copy, shuffling the lru->bh[] array entries > directly.
Yup, that plus making it a ringbuffer maybe.
But I don't recall seeing bh_lru_install() standing out on profiles. I expect that when the system is working hard we're averaging nearly zero cache misses in that copy. Do you really think it is worth optimising? - 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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