>>>>> "Andi" == Andi Kleen <andi@xxxxxxxxxxxxxx> writes: Andi> Doesn't have any performance numbers. It's been a while since I read them. I thought they had some compelling numbers. Anyway, made a big difference in real life testing here. For sustained I/O we're talking an order of magnitude. Andi> You need to keep in mind that PCLMULQDQ uses FPU state, so any Andi> speedup for the kernel must be large enough to amortize the cost Andi> of saving the FPU state. Yeah, my test cases were for bulk database I/O, not for writing a handful of fs metadata blocks. Plus for the DB tests the CRC was generated in userland. I seem to recall Joel picking something other than the hw-accelerated CRC32C for ocfs2 metadata and that didn't cause any problems. That said, I do see a difference between IP checksum and CRC on normal FS workloads with DIX enabled here. Andi> Typically that only works out for quite large buffers, but kernel Andi> buffers are relatively small. *nod* -- Martin K. Petersen Oracle Linux Engineering -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
