Messages in this thread Patch in this message | | | Date | Fri, 29 Jul 2005 10:35:58 +0200 | From | Ingo Molnar <> | Subject | Re: Add prefetch switch stack hook in scheduler function |
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* Chen, Kenneth W <kenneth.w.chen@intel.com> wrote:
> Ingo Molnar wrote on Friday, July 29, 2005 12:07 AM > > the patch below unrolls the prefetch_range() loop manually, for up to 5 > > cachelines prefetched. This patch, ontop of the 4 previous patches, > > should generate similar code to the assembly code in your original > > patch. The full patch-series is: > > It generate slight different code because previous patch asks for a little > over 5 cache lines worth of bytes and it always go to the for loop.
ok - fix below. But i'm not that sure we want to unroll a 6-instruction loop, and it's getting a bit ugly. (Also, it would be nice to have a gcc extension for loops that says 'always unroll up to N entries'.)
Ingo
---- unroll the prefetch loop some more.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
include/linux/prefetch.h | 16 ++++++++++++++++ 1 files changed, 16 insertions(+)
Index: linux-prefetch-task/include/linux/prefetch.h =================================================================== --- linux-prefetch-task.orig/include/linux/prefetch.h +++ linux-prefetch-task/include/linux/prefetch.h @@ -87,6 +87,14 @@ static inline void prefetch_range(void * prefetch(cp + 2*PREFETCH_STRIDE); prefetch(cp + 3*PREFETCH_STRIDE); prefetch(cp + 4*PREFETCH_STRIDE); + } + else if (len <= 6*PREFETCH_STRIDE) { + prefetch(cp); + prefetch(cp + PREFETCH_STRIDE); + prefetch(cp + 2*PREFETCH_STRIDE); + prefetch(cp + 3*PREFETCH_STRIDE); + prefetch(cp + 4*PREFETCH_STRIDE); + prefetch(cp + 5*PREFETCH_STRIDE); } else for (; cp < end; cp += PREFETCH_STRIDE) prefetch(cp); @@ -125,6 +133,14 @@ static inline void prefetchw_range(void prefetchw(cp + 2*PREFETCH_STRIDE); prefetchw(cp + 3*PREFETCH_STRIDE); prefetchw(cp + 4*PREFETCH_STRIDE); + } + else if (len <= 6*PREFETCH_STRIDE) { + prefetchw(cp); + prefetchw(cp + PREFETCH_STRIDE); + prefetchw(cp + 2*PREFETCH_STRIDE); + prefetchw(cp + 3*PREFETCH_STRIDE); + prefetchw(cp + 4*PREFETCH_STRIDE); + prefetchw(cp + 5*PREFETCH_STRIDE); } else for (; cp < end; cp += PREFETCH_STRIDE) prefetchw(cp); - 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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