"Michael S. Tsirkin" <mst@xxxxxxxxxx> writes: > On Wed, Feb 27, 2013 at 05:58:37PM +1030, Rusty Russell wrote: >> Paolo Bonzini <pbonzini@xxxxxxxxxx> writes: >> > Il 24/02/2013 23:12, Michael S. Tsirkin ha scritto: >> >> On Tue, Feb 19, 2013 at 06:26:20PM +1030, Rusty Russell wrote: >> >>> virtio_scsi can really use this, to avoid the current hack of copying >> >>> the whole sg array. Some other things get slightly neater, too. >> >>> >> >>> Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx> >> >> >> >> Hmm, this makes add_buf a bit slower. virtio_test results >> >> (I'll send a patch to update the test shortly): >> >> >> >> Before: >> >> 0.09user 0.01system 0:00.12elapsed 91%CPU (0avgtext+0avgdata 480maxresident)k >> >> 0inputs+0outputs (0major+145minor)pagefaults 0swaps >> >> >> >> After: >> >> 0.11user 0.01system 0:00.13elapsed 90%CPU (0avgtext+0avgdata 480maxresident)k >> >> 0inputs+0outputs (0major+145minor)pagefaults 0swaps >> > >> > Not unexpected at all... :( >> > >> > Some of it can be recovered, but if it's 20% I doubt all of it. So my >> > patches were not premature optimization; you really can take just two >> > among speed, flexibility, and having a nice API. >> >> The error bars on this are far too large to say "20%". >> >> Here are my numbers, using 50 runs of: >> time tools/virtio/vringh_test --indirect --eventidx --parallel and >> stats --trim-outliers: >> >> Baseline (before add_sgs): >> 2.840000-3.040000(2.927292)user >> >> After add_sgs: >> 2.970000-3.150000(3.053750)user >> >> After simplifying add_buf a little: >> 2.950000-3.210000(3.081458)user >> >> After inlining virtqueue_add/vring_add_indirect: >> 2.920000-3.150000(3.026875)user >> >> After passing in iteration functions (chained vs unchained): >> 2.760000-2.970000(2.883542)user Oops. This result (and the next) is bogus. I was playing with -O3, and accidentally left that in :( The final result was 3.005208, ie. 3% slowdown. Which almost makes it worth duplicating the whole set of code :( >> After removing the now-unnecessary chain-cleaning in add_buf: >> 2.660000-2.830000(2.753542)user >> >> Any questions? >> Rusty. > > Sorry, so which patches are included in the last stage? > Something I didn't make clear: I tested 2/16 (the patch I replied to). I wanted to tidy them up, add commentry, and integrate your tool cleanup patches first. That's when I noticed my screwup. I'll push them now, but I want to revisit to see if there's something cleverer I can do... Cheers, Rusty. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
