* Avi Kivity <avi@xxxxxxxxxx> wrote: > > I think what would be needed is some non-virtualization speedup example of > > a 'non-special' workload, running on the native/host kernel. 'sort' is an > > interesting usecase - could it be patched to use hugepages if it has to > > sort through lots of data? > > In fact it works well unpatched, the 6% I measured was with the system sort. Yes - but you intentionally sorted something large - the question is, how big is the slowdown with small sizes (if there's a slowdown), where is the break-even point (if any)? > > [...] > > > > Something like GIMP calculations would be a lot more representative of the > > speedup potential. Is it possible to run the GIMP with transparent > > hugepages enabled for it? > > I thought of it, but raster work is too regular so speculative execution > should hide the tlb fill latency. It's also easy to code in a way which > hides cache effects (no idea if it is actually coded that way). Sort showed > a speedup since it defeats branch prediction and thus the processor cannot > pipeline the loop. Would be nice to try because there's a lot of transformations within Gimp - and Gimp can be scripted. It's also a test for negatives: if there is an across-the-board _lack_ of speedups, it shows that it's not really general purpose but more specialistic. If the optimization is specialistic, then that's somewhat of an argument against automatic/transparent handling. (even though even if the beneficiaries turn out to be only special workloads then transparency still has advantages.) > I thought ray tracers with large scenes should show a nice speedup, but > setting this up is beyond my capabilities. Oh, this tickled some memories: x264 compressed encoding can be very cache and TLB intense. Something like the encoding of a 350 MB video file: wget http://media.xiph.org/video/derf/y4m/soccer_4cif.y4m # NOTE: 350 MB! x264 --crf 20 --quiet soccer_4cif.y4m -o /dev/null --threads 4 would be another thing worth trying with transparent-hugetlb enabled. (i've Cc:-ed x264 benchmarking experts - in case i missed something) Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>