| Message ID | 20211027061913.76276-4-xuanzhuo@linux.alibaba.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | virtio support cache indirect desc | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On Wed, 27 Oct 2021 14:19:13 +0800 Xuan Zhuo wrote: > +static bool virtio_desc_cache = true; > module_param(csum, bool, 0444); > module_param(gso, bool, 0444); > module_param(napi_tx, bool, 0644); > +module_param(virtio_desc_cache, bool, 0644); Can this be an ethtool priv flag? module params are discouraged because they can't be controlled per-netdev.
On Thu, Oct 28, 2021 at 9:59 AM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > On Wed, 27 Oct 2021 08:55:28 -0700, Jakub Kicinski <kuba@kernel.org> wrote: > > On Wed, 27 Oct 2021 14:19:13 +0800 Xuan Zhuo wrote: > > > +static bool virtio_desc_cache = true; > > > module_param(csum, bool, 0444); > > > module_param(gso, bool, 0444); > > > module_param(napi_tx, bool, 0644); > > > +module_param(virtio_desc_cache, bool, 0644); > > > > Can this be an ethtool priv flag? module params are discouraged because > > they can't be controlled per-netdev. > > > The current design can only be set when the device is initialized. So using > ethtool to modify it will not work. Anyhow you can add things like synchronization to make it work. But I think what we want is to make it work unconditionally, so having a module parameter seems useless. If you want to use it for benchmarking? Thanks > > Thanks. >
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 4ad25a8b0870..0ec29cf90d0a 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -27,9 +27,11 @@ static int napi_weight = NAPI_POLL_WEIGHT; module_param(napi_weight, int, 0444); static bool csum = true, gso = true, napi_tx = true; +static bool virtio_desc_cache = true; module_param(csum, bool, 0444); module_param(gso, bool, 0444); module_param(napi_tx, bool, 0644); +module_param(virtio_desc_cache, bool, 0644); /* FIXME: MTU in config. */ #define GOOD_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN) @@ -3214,6 +3216,8 @@ static int virtnet_probe(struct virtio_device *vdev) vi->curr_queue_pairs = num_online_cpus(); vi->max_queue_pairs = max_queue_pairs; + virtio_use_desc_cache(vdev, virtio_desc_cache); + /* Allocate/initialize the rx/tx queues, and invoke find_vqs */ err = init_vqs(vi); if (err)
If the VIRTIO_RING_F_INDIRECT_DESC negotiation succeeds, and the number of sgs used for sending packets is greater than 1. We must constantly call __kmalloc/kfree to allocate/release desc. In the case of extremely fast package delivery, the overhead cannot be ignored: 27.46% [kernel] [k] virtqueue_add 16.66% [kernel] [k] detach_buf_split 16.51% [kernel] [k] virtnet_xsk_xmit 14.04% [kernel] [k] virtqueue_add_outbuf 5.18% [kernel] [k] __kmalloc 4.08% [kernel] [k] kfree 2.80% [kernel] [k] virtqueue_get_buf_ctx 2.22% [kernel] [k] xsk_tx_peek_desc 2.08% [kernel] [k] memset_erms 0.83% [kernel] [k] virtqueue_kick_prepare 0.76% [kernel] [k] virtnet_xsk_run 0.62% [kernel] [k] __free_old_xmit_ptr 0.60% [kernel] [k] vring_map_one_sg 0.53% [kernel] [k] native_apic_mem_write 0.46% [kernel] [k] sg_next 0.43% [kernel] [k] sg_init_table 0.41% [kernel] [k] kmalloc_slab Compared to not using virtio indirect cache, virtio-net can get a 16% performance improvement when using indirect desc cache. In the test case, the CPU where the package is sent has reached 100%. The following are the PPS in two cases: indirect desc cache | no cache 3074658 | 2685132 3111866 | 2666118 3152527 | 2653632 3125867 | 2669820 3027147 | 2644464 3069211 | 2669777 3038522 | 2675645 3034507 | 2671302 3102257 | 2685504 3083712 | 2692800 3051771 | 2676928 3080684 | 2695040 3147816 | 2720876 3123887 | 2705492 3180963 | 2699520 3191579 | 2676480 3161670 | 2686272 3189768 | 2692588 3174272 | 2686692 3143434 | 2682416 Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> --- drivers/net/virtio_net.c | 4 ++++ 1 file changed, 4 insertions(+)