在 2023/7/20 16:53, Lei Yang 写道: > According to the Hawkins provided steps, I tested two cases based on > applied this series patches and without it. And all tests are based on > the real hardware. > Case 1, without this series > Source: qemu-system-x86_64: vhost_vdpa_net_load() = 23308 us > Dest: qemu-system-x86_64: vhost_vdpa_net_load() = 23296 us > > Case 2, applied this series > Source: qemu-system-x86_64: vhost_vdpa_net_load() = 6558 us > Dest: qemu-system-x86_64: vhost_vdpa_net_load() = 6539 us > > Tested-by: Lei Yang <leiy...@redhat.com> > > > On Thu, Jul 20, 2023 at 6:54 AM Lei Yang <leiy...@redhat.com> wrote: >> >> On Wed, Jul 19, 2023 at 11:25 PM Hawkins Jiawei <yin31...@gmail.com> wrote: >>> >>> 在 2023/7/19 20:44, Lei Yang 写道: >>>> Hello Hawkins and Michael >>>> >>>> Looks like there are big changes about vp_vdpa, therefore, if needed, >>>> QE can test this series in QE's environment before the patch is >>> >>> Hi Lei, >>> >>> This patch series does not modify the code of vp_vdpa. Instead, it only >>> modifies how QEMU sends SVQ control commands to the vdpa device. >>> >> Hi Hawkins >> >>> Considering that the behavior of the vp_vdpa device differs from that >>> of real vdpa hardware, would it be possible for you to test this patch >>> series on a real vdpa device? >> >> Yes, there is a hardware device to test it , I will update the test >> results ASAP. >> >> BR >> Lei >>> >>> Thanks! >>> >>> >>>> merged, and provide the result. >>>> >>>> BR >>>> Lei >>>> >>>> >>>> On Wed, Jul 19, 2023 at 8:37 PM Hawkins Jiawei <yin31...@gmail.com> wrote: >>>>> >>>>> 在 2023/7/19 17:11, Michael S. Tsirkin 写道: >>>>>> On Wed, Jul 19, 2023 at 03:53:45PM +0800, Hawkins Jiawei wrote: >>>>>>> This patchset allows QEMU to delay polling and checking the device >>>>>>> used buffer until either the SVQ is full or control commands shadow >>>>>>> buffers are full, 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 vp_vdpa device to simulate vdpa device, and create 4094 VLANS in >>>>>>> guest to build a test environment for sending multiple CVQ state load >>>>>>> commands. This patch series can improve latency from 10023 us to >>>>>>> 8697 us for about 4099 CVQ state load commands, about 0.32 us per >>>>>>> command.
It appears that the performance timing with the vp_vdpa device in this method is not consistently stable. I retest this patch series with the same steps with the vp_vdpa device. With this patch series, in the majority of cases, the time for CVQ state load commands is around 8000 us ~ 10000 us. Without this patch series, in the majority of cases, the time for CVQ state load commands is around 14000 us ~ 20000 us. Thanks! >>>>>> >>>>>> Looks like a tiny improvement. >>>>>> At the same time we have O(n^2) behaviour with memory mappings. >>>>> >>>>> Hi Michael, >>>>> >>>>> Thanks for your review. >>>>> >>>>> I wonder why you say "we have O(n^2) behaviour on memory mappings" here? >>>>> >>>>> From my understanding, QEMU maps two page-size buffers as control >>>>> commands shadow buffers at device startup. These buffers then are used >>>>> to cache SVQ control commands, where QEMU fills them with multiple SVQ >>>>> control >>>>> commands bytes, flushes them when SVQ descriptors are full or these >>>>> control commands shadow buffers reach their capacity. >>>>> >>>>> QEMU repeats this process until all CVQ state load commands have been >>>>> sent in loading. >>>>> >>>>> In this loading process, only control commands shadow buffers >>>>> translation should be relative to memory mappings, which should be >>>>> O(log n) behaviour to my understanding(Please correct me if I am wrong). >>>>> >>>>>> Not saying we must not do this but I think it's worth >>>>>> checking where the bottleneck is. My guess would be >>>>>> vp_vdpa is not doing things in parallel. Want to try fixing that >>>>> >>>>> As for "vp_vdpa is not doing things in parallel.", do you mean >>>>> the vp_vdpa device cannot process QEMU's SVQ control commands >>>>> in parallel? >>>>> >>>>> In this situation, I will try to use real vdpa hardware to >>>>> test the patch series performance. >>>>> >>>>>> to see how far it can be pushed? >>>>> >>>>> Currently, I am involved in the "Add virtio-net Control Virtqueue state >>>>> restore support" project in Google Summer of Code now. Because I am >>>>> uncertain about the time it will take to fix that problem in the vp_vdpa >>>>> device, I prefer to complete the gsoc project first. >>>>> >>>>> Thanks! >>>>> >>>>> >>>>>> >>>>>> >>>>>>> Note that this patch should be based on >>>>>>> patch "Vhost-vdpa Shadow Virtqueue VLAN support" at [1]. >>>>>>> >>>>>>> [1]. https://lists.gnu.org/archive/html/qemu-devel/2023-07/msg03719.html >>>>>>> >>>>>>> TestStep >>>>>>> ======== >>>>>>> 1. regression testing using vp-vdpa device >>>>>>> - For L0 guest, boot QEMU with two virtio-net-pci net device with >>>>>>> `ctrl_vq`, `ctrl_rx`, `ctrl_rx_extra` features on, command line like: >>>>>>> -device virtio-net-pci,disable-legacy=on,disable-modern=off, >>>>>>> iommu_platform=on,mq=on,ctrl_vq=on,guest_announce=off, >>>>>>> indirect_desc=off,queue_reset=off,ctrl_rx=on,ctrl_rx_extra=on,... >>>>>>> >>>>>>> - For L1 guest, apply the patch series and compile the source code, >>>>>>> start QEMU with two vdpa device with svq mode on, enable the `ctrl_vq`, >>>>>>> `ctrl_rx`, `ctrl_rx_extra` features on, command line like: >>>>>>> -netdev type=vhost-vdpa,x-svq=true,... >>>>>>> -device virtio-net-pci,mq=on,guest_announce=off,ctrl_vq=on, >>>>>>> ctrl_rx=on,ctrl_rx_extra=on... >>>>>>> >>>>>>> - For L2 source guest, run the following bash command: >>>>>>> ```bash >>>>>>> #!/bin/sh >>>>>>> >>>>>>> for idx1 in {0..9} >>>>>>> do >>>>>>> for idx2 in {0..9} >>>>>>> do >>>>>>> for idx3 in {0..6} >>>>>>> do >>>>>>> ip link add macvlan$idx1$idx2$idx3 link eth0 >>>>>>> address 4a:30:10:19:$idx1$idx2:1$idx3 type macvlan mode bridge >>>>>>> ip link set macvlan$idx1$idx2$idx3 up >>>>>>> done >>>>>>> done >>>>>>> done >>>>>>> ``` >>>>>>> - Execute the live migration in L2 source monitor >>>>>>> >>>>>>> - Result >>>>>>> * with this series, QEMU should not trigger any error or warning. >>>>>>> >>>>>>> >>>>>>> >>>>>>> 2. perf using vp-vdpa device >>>>>>> - For L0 guest, boot QEMU with two virtio-net-pci net device with >>>>>>> `ctrl_vq`, `ctrl_vlan` features on, command line like: >>>>>>> -device virtio-net-pci,disable-legacy=on,disable-modern=off, >>>>>>> iommu_platform=on,mq=on,ctrl_vq=on,guest_announce=off, >>>>>>> indirect_desc=off,queue_reset=off,ctrl_vlan=on,... >>>>>>> >>>>>>> - For L1 guest, apply the patch series, then apply an addtional >>>>>>> patch to record the load time in microseconds as following: >>>>>>> ```diff >>>>>>> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c >>>>>>> index 6b958d6363..501b510fd2 100644 >>>>>>> --- a/hw/net/vhost_net.c >>>>>>> +++ b/hw/net/vhost_net.c >>>>>>> @@ -295,7 +295,10 @@ static int vhost_net_start_one(struct vhost_net >>>>>>> *net, >>>>>>> } >>>>>>> >>>>>>> if (net->nc->info->load) { >>>>>>> + int64_t start_us = g_get_monotonic_time(); >>>>>>> r = net->nc->info->load(net->nc); >>>>>>> + error_report("vhost_vdpa_net_load() = %ld us", >>>>>>> + g_get_monotonic_time() - start_us); >>>>>>> if (r < 0) { >>>>>>> goto fail; >>>>>>> } >>>>>>> ``` >>>>>>> >>>>>>> - For L1 guest, compile the code, and start QEMU with two vdpa >>>>>>> device >>>>>>> with svq mode on, enable the `ctrl_vq`, `ctrl_vlan` features on, >>>>>>> command line like: >>>>>>> -netdev type=vhost-vdpa,x-svq=true,... >>>>>>> -device virtio-net-pci,mq=on,guest_announce=off,ctrl_vq=on, >>>>>>> ctrl_vlan=on... >>>>>>> >>>>>>> - For L2 source guest, run the following bash command: >>>>>>> ```bash >>>>>>> #!/bin/sh >>>>>>> >>>>>>> for idx in {1..4094} >>>>>>> do >>>>>>> ip link add link eth0 name vlan$idx type vlan id $idx >>>>>>> done >>>>>>> ``` >>>>>>> >>>>>>> - wait for some time, then execute the live migration in L2 source >>>>>>> monitor >>>>>>> >>>>>>> - Result >>>>>>> * with this series, QEMU should not trigger any warning >>>>>>> or error except something like "vhost_vdpa_net_load() = 8697 us" >>>>>>> * without this series, QEMU should not trigger any warning >>>>>>> or error except something like "vhost_vdpa_net_load() = 10023 us" >>>>>>> >>>>>>> ChangeLog >>>>>>> ========= >>>>>>> v3: >>>>>>> - refactor vhost_svq_poll() to accept cmds_in_flight >>>>>>> suggested by Jason and Eugenio >>>>>>> - refactor vhost_vdpa_net_cvq_add() to make control commands >>>>>>> buffers >>>>>>> is not tied to `s->cvq_cmd_out_buffer` and `s->status`, so we can reuse >>>>>>> it suggested by Eugenio >>>>>>> - poll and check when SVQ is full or control commands shadow >>>>>>> buffers is >>>>>>> full >>>>>>> >>>>>>> v2: https://lore.kernel.org/all/cover.1683371965.git.yin31...@gmail.com/ >>>>>>> - recover accidentally deleted rows >>>>>>> - remove extra newline >>>>>>> - refactor `need_poll_len` to `cmds_in_flight` >>>>>>> - return -EINVAL when vhost_svq_poll() return 0 or check >>>>>>> on buffers written by device fails >>>>>>> - change the type of `in_cursor`, and refactor the >>>>>>> code for updating cursor >>>>>>> - return directly when vhost_vdpa_net_load_{mac,mq}() >>>>>>> returns a failure in vhost_vdpa_net_load() >>>>>>> >>>>>>> v1: https://lore.kernel.org/all/cover.1681732982.git.yin31...@gmail.com/ >>>>>>> >>>>>>> Hawkins Jiawei (8): >>>>>>> vhost: Add argument to vhost_svq_poll() >>>>>>> vdpa: Use iovec for vhost_vdpa_net_cvq_add() >>>>>>> vhost: Expose vhost_svq_available_slots() >>>>>>> vdpa: Avoid using vhost_vdpa_net_load_*() outside >>>>>>> vhost_vdpa_net_load() >>>>>>> vdpa: Check device ack in vhost_vdpa_net_load_rx_mode() >>>>>>> vdpa: Move vhost_svq_poll() to the caller of >>>>>>> vhost_vdpa_net_cvq_add() >>>>>>> vdpa: Add cursors to vhost_vdpa_net_loadx() >>>>>>> vdpa: Send cvq state load commands in parallel >>>>>>> >>>>>>> hw/virtio/vhost-shadow-virtqueue.c | 38 ++-- >>>>>>> hw/virtio/vhost-shadow-virtqueue.h | 3 +- >>>>>>> net/vhost-vdpa.c | 354 >>>>>>> ++++++++++++++++++----------- >>>>>>> 3 files changed, 249 insertions(+), 146 deletions(-) >>>>>>> >>>>>>> -- >>>>>>> 2.25.1 >>>>>> >>>>> >>>> >>> >
