On Wed, Nov 06, 2013 at 09:19:23AM -0800, Joe Perches wrote: > On Wed, 2013-11-06 at 10:54 -0500, Neil Horman wrote: > > On Wed, Nov 06, 2013 at 10:34:29AM -0500, Dave Jones wrote: > > > On Wed, Nov 06, 2013 at 10:23:19AM -0500, Neil Horman wrote: > > > > do_csum was identified via perf recently as a hot spot when doing > > > > receive on ip over infiniband workloads. After alot of testing and > > > > ideas, we found the best optimization available to us currently is to > > > > prefetch the entire data buffer prior to doing the checksum > [] > > I'll fix this up and send a v3, but I'll give it a day in case there are > > more > > comments first. > > Perhaps a reduction in prefetch loop count helps. > > Was capping the amount prefetched and letting the > hardware prefetch also tested? > > prefetch_lines(buff, min(len, cache_line_size() * 8u)); >
Just tested this out: With limiting: 1500B | 64MB | 1000000 | 1.344167 1500B | 128MB | 1000000 | 1.340970 1500B | 256MB | 1000000 | 1.353562 1500B | 512MB | 1000000 | 1.346349 9000B | 64MB | 1000000 | 0.852174 9000B | 128MB | 1000000 | 0.852765 9000B | 256MB | 1000000 | 0.853153 9000B | 512MB | 1000000 | 0.852661 64KB | 64MB | 1000000 | 0.768585 64KB | 128MB | 1000000 | 0.769465 64KB | 256MB | 1000000 | 0.769909 64KB | 512MB | 1000000 | 0.779895 Without limiting 1500B | 64MB | 1000000 | 1.360525 1500B | 128MB | 1000000 | 1.354220 1500B | 256MB | 1000000 | 1.371037 1500B | 512MB | 1000000 | 1.353557 9000B | 64MB | 1000000 | 0.850415 9000B | 128MB | 1000000 | 0.853642 9000B | 256MB | 1000000 | 0.852048 9000B | 512MB | 1000000 | 0.852484 64KB | 64MB | 1000000 | 0.768261 64KB | 128MB | 1000000 | 0.768566 64KB | 256MB | 1000000 | 0.770822 64KB | 512MB | 1000000 | 0.769391 Doesn't look like much consistent improvement. Neil -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
