On 11/12/2015 06:16 PM, Jason Wang wrote: > Hi all: > > 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 were done through: > > - 50 us as busy loop timeout > - Netperf 2.6 > - Two machines with back to back connected ixgbe > - Guest with 1 vcpu and 1 queue > > Results: > - For stream workload, ioexits were reduced dramatically in medium > size (1024-2048) of tx (at most -39%) and almost all rx (at most > -79%) as a result of polling. This compensate for the possible > wasted cpu cycles more or less. That porbably why we can still see > some increasing in the normalized throughput in some cases. > - Throughput of tx were increased (at most 105%) expect for the huge > write (16384). And we can send more packets in the case (+tpkts were > increased). > - Very minor rx regression in some cases. > - Improvemnt on TCP_RR (at most 16%). Forget to mention, the following test results by order are: 1) Guest TX 2) Guest RX 3) TCP_RR > size/session/+thu%/+normalize%/+tpkts%/+rpkts%/+ioexits%/ > 64/ 1/ +9%/ -17%/ +5%/ +10%/ -2% > 64/ 2/ +8%/ -18%/ +6%/ +10%/ -1% > 64/ 4/ +4%/ -21%/ +6%/ +10%/ -1% > 64/ 8/ +9%/ -17%/ +6%/ +9%/ -2% > 256/ 1/ +20%/ -1%/ +15%/ +11%/ -9% > 256/ 2/ +15%/ -6%/ +15%/ +8%/ -8% > 256/ 4/ +17%/ -4%/ +16%/ +8%/ -8% > 256/ 8/ -61%/ -69%/ +16%/ +10%/ -10% > 512/ 1/ +15%/ -3%/ +19%/ +18%/ -11% > 512/ 2/ +19%/ 0%/ +19%/ +13%/ -10% > 512/ 4/ +18%/ -2%/ +18%/ +15%/ -10% > 512/ 8/ +17%/ -1%/ +18%/ +15%/ -11% > 1024/ 1/ +25%/ +4%/ +27%/ +16%/ -21% > 1024/ 2/ +28%/ +8%/ +25%/ +15%/ -22% > 1024/ 4/ +25%/ +5%/ +25%/ +14%/ -21% > 1024/ 8/ +27%/ +7%/ +25%/ +16%/ -21% > 2048/ 1/ +32%/ +12%/ +31%/ +22%/ -38% > 2048/ 2/ +33%/ +12%/ +30%/ +23%/ -36% > 2048/ 4/ +31%/ +10%/ +31%/ +24%/ -37% > 2048/ 8/ +105%/ +75%/ +33%/ +23%/ -39% > 16384/ 1/ 0%/ -14%/ +2%/ 0%/ +19% > 16384/ 2/ 0%/ -13%/ +19%/ -13%/ +17% > 16384/ 4/ 0%/ -12%/ +3%/ 0%/ +2% > 16384/ 8/ 0%/ -11%/ -2%/ +1%/ +1% > size/session/+thu%/+normalize%/+tpkts%/+rpkts%/+ioexits%/ > 64/ 1/ -7%/ -23%/ +4%/ +6%/ -74% > 64/ 2/ -2%/ -12%/ +2%/ +2%/ -55% > 64/ 4/ +2%/ -5%/ +10%/ -2%/ -43% > 64/ 8/ -5%/ -5%/ +11%/ -34%/ -59% > 256/ 1/ -6%/ -16%/ +9%/ +11%/ -60% > 256/ 2/ +3%/ -4%/ +6%/ -3%/ -28% > 256/ 4/ 0%/ -5%/ -9%/ -9%/ -10% > 256/ 8/ -3%/ -6%/ -12%/ -9%/ -40% > 512/ 1/ -4%/ -17%/ -10%/ +21%/ -34% > 512/ 2/ 0%/ -9%/ -14%/ -3%/ -30% > 512/ 4/ 0%/ -4%/ -18%/ -12%/ -4% > 512/ 8/ -1%/ -4%/ -1%/ -5%/ +4% > 1024/ 1/ 0%/ -16%/ +12%/ +11%/ -10% > 1024/ 2/ 0%/ -11%/ 0%/ +5%/ -31% > 1024/ 4/ 0%/ -4%/ -7%/ +1%/ -22% > 1024/ 8/ -5%/ -6%/ -17%/ -29%/ -79% > 2048/ 1/ 0%/ -16%/ +1%/ +9%/ -10% > 2048/ 2/ 0%/ -12%/ +7%/ +9%/ -26% > 2048/ 4/ 0%/ -7%/ -4%/ +3%/ -64% > 2048/ 8/ -1%/ -5%/ -6%/ +4%/ -20% > 16384/ 1/ 0%/ -12%/ +11%/ +7%/ -20% > 16384/ 2/ 0%/ -7%/ +1%/ +5%/ -26% > 16384/ 4/ 0%/ -5%/ +12%/ +22%/ -23% > 16384/ 8/ 0%/ -1%/ -8%/ +5%/ -3% > size/session/+thu%/+normalize%/+tpkts%/+rpkts%/+ioexits%/ > 1/ 1/ +9%/ -29%/ +9%/ +9%/ +9% > 1/ 25/ +6%/ -18%/ +6%/ +6%/ -1% > 1/ 50/ +6%/ -19%/ +5%/ +5%/ -2% > 1/ 100/ +5%/ -19%/ +4%/ +4%/ -3% > 64/ 1/ +10%/ -28%/ +10%/ +10%/ +10% > 64/ 25/ +8%/ -18%/ +7%/ +7%/ -2% > 64/ 50/ +8%/ -17%/ +8%/ +8%/ -1% > 64/ 100/ +8%/ -17%/ +8%/ +8%/ -1% > 256/ 1/ +10%/ -28%/ +10%/ +10%/ +10% > 256/ 25/ +15%/ -13%/ +15%/ +15%/ 0% > 256/ 50/ +16%/ -14%/ +18%/ +18%/ +2% > 256/ 100/ +15%/ -13%/ +12%/ +12%/ -2% > > Changes from 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 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_more_avail() > vhost_net: basic polling support > > drivers/vhost/net.c | 77 +++++++++++++++++++++++++++++++++++++++++++--- > drivers/vhost/vhost.c | 48 +++++++++++++++++++++++------ > drivers/vhost/vhost.h | 3 ++ > include/uapi/linux/vhost.h | 11 +++++++ > 4 files changed, 125 insertions(+), 14 deletions(-) > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
