On Saturday 30 December 2006 23:08, Robert P. J. Day wrote: > > > > clear_page assumes that given address is page aligned, I think. It > > may fail if you feed it with misaligned region's address. > > i don't see how that can be true, given that most of the definitions > of the clear_page() macro are simply invocations of memset(). see for > yourself: > > $ grep -r "#define clear_page" include > > my only point here was that lots of code seems to be calling memset() > when it would be clearer to invoke clear_page(). but there's still > something a bit curious happening here. i'll poke around a bit more > before i ask, though.
There are MMX implementations of clear_page(). I was experimenting with SSE[2] clear_page() which uses non-temporal stores. That one requires 16 byte alignment. BTW, it worked ~300% faster than memset. But Andi Kleen insists that cache eviction caused by NT stores will make it slower in macrobenchmark. Apart from fairly extensive set of microbechmarks I tested kernel compiles (i.e. "real world load") and they are FASTER too, not slower, but Andi is fairly entrenched in his opinion ;) I gave up. -- vda - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
