Messages in this thread | | | Date | Sun, 6 Jan 2002 05:51:47 -0800 | From | William Lee Irwin III <> | Subject | Re: [PATCH] Remove 8 bytes from struct page on 64bit archs |
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On Mon, Jan 07, 2002 at 12:33:26AM +1100, Anton Blanchard wrote: > For archs that need ->zone, merging it with ->flags sounds like a > great idea. Id like to cram something into ->flags on 64 bit archs > since its only a long due to bitop constraints. I had thought of > stuffing ->count in the high word but now Im just getting silly > since all non atomic accesses to ->flags would then have to be word > ones.
At some point in the past, I wrote: >> My i386 version, which makes ->virtual conditional on CONFIG_HIGHMEM as >> well, is at:
On Mon, Jan 07, 2002 at 12:33:26AM +1100, Anton Blanchard wrote: > Id like to do redo some profiling, on ppc64 we had page_address() doing > pointer arithmetic (instead of page->virtual) and the compiler created > an awful sequence of instructions in the acenic interrupt handler. > A zero copy TCP benchmark made it rather obvious.
I'm not entirely surprised at this, CONFIG_HIGHMEM is probably just not quite a strict enough criterion for eliminating ->virtual as it's a time/space tradeoff that just happens to be bad on ppc64. Maybe we should figure out some other criterion in addition to it.
Cheers, Bill - 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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