On Fri, 4 Mar 2016 06:24:50 -0500 Jason Wang <jasowang@xxxxxxxxxx> wrote: > This series tries to add basic busy polling for vhost net. The idea is > simple: at the end of tx/rx processing, busy polling for new tx added > descriptor and rx receive socket for a while. The maximum number of > time (in us) could be spent on busy polling was specified ioctl. > > Test A were done through: > > - 50 us as busy loop timeout > - Netperf 2.6 > - Two machines with back to back connected mlx4 Hi Jason, Could this also improve performance if both VMs are on the same host system ? > - Guest with 1 vcpus and 1 queue > > Results: > - Obvious improvements (%5 - 20%) for latency (TCP_RR). > - Get a better or minor regression on most of the TX tests, but see > some regression on 4096 size. > - Except for 8 sessions of 4096 size RX, have a better or same > performance. > - CPU utilization were incrased as expected. > > TCP_RR: > size/session/+thu%/+normalize%/+tpkts%/+rpkts%/+ioexits%/ > 1/ 1/ +8%/ -32%/ +8%/ +8%/ +7% > 1/ 50/ +7%/ -19%/ +7%/ +7%/ +1% > 1/ 100/ +5%/ -21%/ +5%/ +5%/ 0% > 1/ 200/ +5%/ -21%/ +7%/ +7%/ +1% > 64/ 1/ +11%/ -29%/ +11%/ +11%/ +10% > 64/ 50/ +7%/ -19%/ +8%/ +8%/ +2% > 64/ 100/ +8%/ -18%/ +9%/ +9%/ +2% > 64/ 200/ +6%/ -19%/ +6%/ +6%/ 0% > 256/ 1/ +7%/ -33%/ +7%/ +7%/ +6% > 256/ 50/ +7%/ -18%/ +7%/ +7%/ 0% > 256/ 100/ +9%/ -18%/ +8%/ +8%/ +2% > 256/ 200/ +9%/ -18%/ +10%/ +10%/ +3% > 1024/ 1/ +20%/ -28%/ +20%/ +20%/ +19% > 1024/ 50/ +8%/ -18%/ +9%/ +9%/ +2% > 1024/ 100/ +6%/ -19%/ +5%/ +5%/ 0% > 1024/ 200/ +8%/ -18%/ +9%/ +9%/ +2% > Guest TX: > size/session/+thu%/+normalize%/+tpkts%/+rpkts%/+ioexits%/ > 64/ 1/ -5%/ -28%/ +11%/ +12%/ +10% > 64/ 4/ -2%/ -26%/ +13%/ +13%/ +13% > 64/ 8/ -6%/ -29%/ +9%/ +10%/ +10% > 512/ 1/ +15%/ -7%/ +13%/ +11%/ +3% > 512/ 4/ +17%/ -6%/ +18%/ +13%/ +11% > 512/ 8/ +14%/ -7%/ +13%/ +7%/ +7% > 1024/ 1/ +27%/ -2%/ +26%/ +29%/ +12% > 1024/ 4/ +8%/ -9%/ +6%/ +1%/ +6% > 1024/ 8/ +41%/ +12%/ +34%/ +20%/ -3% > 4096/ 1/ -22%/ -21%/ -36%/ +81%/+1360% > 4096/ 4/ -57%/ -58%/ +286%/ +15%/+2074% > 4096/ 8/ +67%/ +70%/ -45%/ -8%/ +63% > 16384/ 1/ -2%/ -5%/ +5%/ -3%/ +80% > 16384/ 4/ 0%/ 0%/ 0%/ +4%/ +138% > 16384/ 8/ 0%/ 0%/ 0%/ +1%/ +41% > 65535/ 1/ -3%/ -6%/ +2%/ +11%/ +113% > 65535/ 4/ -2%/ -1%/ -2%/ -3%/ +484% > 65535/ 8/ 0%/ +1%/ 0%/ +2%/ +40% > Guest RX: > size/session/+thu%/+normalize%/+tpkts%/+rpkts%/+ioexits%/ > 64/ 1/ +31%/ -3%/ +8%/ +8%/ +8% > 64/ 4/ +11%/ -17%/ +13%/ +14%/ +15% > 64/ 8/ +4%/ -23%/ +11%/ +11%/ +12% > 512/ 1/ +24%/ 0%/ +18%/ +14%/ -8% > 512/ 4/ +4%/ -15%/ +6%/ +5%/ +6% > 512/ 8/ +26%/ 0%/ +21%/ +10%/ +3% > 1024/ 1/ +88%/ +47%/ +69%/ +44%/ -30% > 1024/ 4/ +18%/ -5%/ +19%/ +16%/ +2% > 1024/ 8/ +15%/ -4%/ +13%/ +8%/ +1% > 4096/ 1/ -3%/ -5%/ +2%/ -2%/ +41% > 4096/ 4/ +2%/ +3%/ -20%/ -14%/ -24% > 4096/ 8/ -43%/ -45%/ +69%/ -24%/ +94% > 16384/ 1/ -3%/ -11%/ +23%/ +7%/ +42% > 16384/ 4/ -3%/ -3%/ -4%/ +5%/ +115% > 16384/ 8/ -1%/ 0%/ -1%/ -3%/ +32% > 65535/ 1/ +1%/ 0%/ +2%/ 0%/ +66% > 65535/ 4/ -1%/ -1%/ 0%/ +4%/ +492% > 65535/ 8/ 0%/ -1%/ -1%/ +4%/ +38% > > Changes from V3: > - drop single_task_running() > - use cpu_relax_lowlatency() instead of cpu_relax() > > Changes from V2: > - rename vhost_vq_more_avail() to vhost_vq_avail_empty(). And return > false we __get_user() fails. > - do not bother premmptions/timers for good path. > - use vhost_vring_state as ioctl parameter instead of reinveting a new > one. > - add the unit of timeout (us) to the comment of new added ioctls > > Changes from V1: > - remove the buggy vq_error() in vhost_vq_more_avail(). > - leave vhost_enable_notify() untouched. > > Changes from RFC V3: > - small tweak on the code to avoid multiple duplicate conditions in > critical path when busy loop is not enabled. > - add the test result of multiple VMs > > Changes from RFC V2: > - poll also at the end of rx handling > - factor out the polling logic and optimize the code a little bit > - add two ioctls to get and set the busy poll timeout > - test on ixgbe (which can give more stable and reproducable numbers) > instead of mlx4. > > Changes from RFC V1: > - add a comment for vhost_has_work() to explain why it could be > lockless > - add param description for busyloop_timeout > - split out the busy polling logic into a new helper > - check and exit the loop when there's a pending signal > - disable preemption during busy looping to make sure lock_clock() was > correctly used. > > Jason Wang (3): > vhost: introduce vhost_has_work() > vhost: introduce vhost_vq_avail_empty() > vhost_net: basic polling support > > drivers/vhost/net.c | 78 +++++++++++++++++++++++++++++++++++++++++++--- > drivers/vhost/vhost.c | 35 +++++++++++++++++++++ > drivers/vhost/vhost.h | 3 ++ > include/uapi/linux/vhost.h | 6 ++++ > 4 files changed, 117 insertions(+), 5 deletions(-) > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
