On Thu, 20 Apr 2023 at 01:17, Eugenio Perez Martin <epere...@redhat.com> wrote: > > On Wed, Apr 19, 2023 at 1:50 PM Hawkins Jiawei <yin31...@gmail.com> wrote: > > > > This patchset allows QEMU to poll and check the device used buffer > > after sending all SVQ control commands, instead of polling and checking > > immediately after sending each SVQ control command, so that QEMU can > > send all the SVQ control commands in parallel, which have better > > performance improvement. > > > > I use vdpa_sim_net to simulate vdpa device, refactor > > vhost_vdpa_net_load() to call vhost_vdpa_net_load_mac() 30 times, > > refactor `net_vhost_vdpa_cvq_info.load` to call vhost_vdpa_net_load() > > 1000 times, > > Maybe a little bit too high for real scenarios but it gives us a hint > for sure :). Maybe it is more realistic to send ~10 or ~100 commands?
Yes, it is absolutely too high for real scenarios to call vhost_vdpa_net_load() 1000 times. But considering that the time to execute vhost_vdpa_net_load_mac() 30 times is very short, the result time may be highly unstable and fluctuate greatly, so I call vhost_vdpa_net_load() 1000 times, hoping to get a more stable result. > > > to build a test environment for sending > > multiple SVQ control commands. Time in monotonic to > > finish `net_vhost_vdpa_cvq_info.load`: > > > > QEMU monotonic time > > -------------------------------------------------- > > not patched 89202 > > -------------------------------------------------- > > patched 80455 > > > > Is time expressed in seconds or milliseconds? I'm going to assume ms. I got this by calling g_get_monotonic_time(), it should be microseconds according to [1]. [1]. https://docs.gtk.org/glib/func.get_monotonic_time.html > > So let's say all the time was spent in the context switch between qemu > and kernel, this is a save of (89202 - 80455)/30000 = 0.3 ms per > command? Yes, I think it is a save of 0.3 microseconds per command. Thanks! > > Thanks! > > > This patchset resolves the GitLab issue at > > https://gitlab.com/qemu-project/qemu/-/issues/1578. > > > > Hawkins Jiawei (2): > > vdpa: rename vhost_vdpa_net_cvq_add() > > vdpa: send CVQ state load commands in parallel > > > > net/vhost-vdpa.c | 150 +++++++++++++++++++++++++++++++++++------------ > > 1 file changed, 112 insertions(+), 38 deletions(-) > > > > -- > > 2.25.1 > > >
