Wed, Jun 19, 2024 at 10:23:25AM CEST, mst@xxxxxxxxxx wrote:
>On Wed, Jun 19, 2024 at 10:05:41AM +0200, Jiri Pirko wrote:
>> >Oh. Right of course. Worth a comment maybe? Just to make sure
>> >we remember not to call __free_old_xmit twice in a row
>> >without reinitializing stats.
>> >Or move the initialization into __free_old_xmit to make it
>> >self-contained ..
>>
>> Well, the initialization happens in the caller by {0}, Wouldn't
>> memset in __free_old_xmit() add an extra overhead? IDK.
>
>
>Well if I did the below the binary is a bit smaller.
>
>If you have to respin you can include it.
>If not I can submit separately.
Please send it reparately. It's should be a separate patch.
Thanks!
>
>----
>
>
>virtio-net: cleanup __free_old_xmit
>
>Two call sites of __free_old_xmit zero-initialize stats,
>doing it inside __free_old_xmit seems to make compiler's
>job a bit easier:
>
>$ size /tmp/orig/virtio_net.o
> text data bss dec hex filename
> 65857 3892 100 69849 110d9 /tmp/orig/virtio_net.o
>$ size /tmp/new/virtio_net.o
> text data bss dec hex filename
> 65760 3892 100 69752 11078 /tmp/new/virtio_net.o
>
>Couldn't measure any performance impact, unsurprizingly.
>
>Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
>
>---
>
>diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>index 283b34d50296..c2ce8de340f7 100644
>--- a/drivers/net/virtio_net.c
>+++ b/drivers/net/virtio_net.c
>@@ -383,6 +383,8 @@ static void __free_old_xmit(struct send_queue *sq, bool in_napi,
> unsigned int len;
> void *ptr;
>
>+ stats->bytes = stats->packets = 0;
Memset perhaps?
>+
> while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
> ++stats->packets;
>
>@@ -828,7 +830,7 @@ static void virtnet_rq_unmap_free_buf(struct virtqueue *vq, void *buf)
>
> static void free_old_xmit(struct send_queue *sq, bool in_napi)
> {
>- struct virtnet_sq_free_stats stats = {0};
>+ struct virtnet_sq_free_stats stats;
>
> __free_old_xmit(sq, in_napi, &stats);
>
>@@ -979,7 +981,7 @@ static int virtnet_xdp_xmit(struct net_device *dev,
> int n, struct xdp_frame **frames, u32 flags)
> {
> struct virtnet_info *vi = netdev_priv(dev);
>- struct virtnet_sq_free_stats stats = {0};
>+ struct virtnet_sq_free_stats stats;
> struct receive_queue *rq = vi->rq;
> struct bpf_prog *xdp_prog;
> struct send_queue *sq;
>
