On Wed, Jun 19, 2024 at 10:05:41AM +0200, Jiri Pirko wrote:
> Wed, Jun 19, 2024 at 09:26:22AM CEST, mst@xxxxxxxxxx wrote:
> >On Wed, Jun 19, 2024 at 07:45:16AM +0200, Jiri Pirko wrote:
> >> Tue, Jun 18, 2024 at 08:18:12PM CEST, mst@xxxxxxxxxx wrote:
> >> >This looks like a sensible way to do this.
> >> >Yet something to improve:
> >> >
> >> >
> >> >On Tue, Jun 18, 2024 at 04:44:56PM +0200, Jiri Pirko wrote:
> >> >> From: Jiri Pirko <jiri@xxxxxxxxxx>
> >> >>
> >>
> >> [...]
> >>
> >>
> >> >> +static void __free_old_xmit(struct send_queue *sq, struct netdev_queue *txq,
> >> >> + bool in_napi, struct virtnet_sq_free_stats *stats)
> >> >> {
> >> >> unsigned int len;
> >> >> void *ptr;
> >> >>
> >> >> while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
> >> >> - ++stats->packets;
> >> >> -
> >> >> if (!is_xdp_frame(ptr)) {
> >> >> - struct sk_buff *skb = ptr;
> >> >> + struct sk_buff *skb = ptr_to_skb(ptr);
> >> >>
> >> >> pr_debug("Sent skb %p\n", skb);
> >> >>
> >> >> - stats->bytes += skb->len;
> >> >> + if (is_orphan_skb(ptr)) {
> >> >> + stats->packets++;
> >> >> + stats->bytes += skb->len;
> >> >> + } else {
> >> >> + stats->napi_packets++;
> >> >> + stats->napi_bytes += skb->len;
> >> >> + }
> >> >> napi_consume_skb(skb, in_napi);
> >> >> } else {
> >> >> struct xdp_frame *frame = ptr_to_xdp(ptr);
> >> >>
> >> >> + stats->packets++;
> >> >> stats->bytes += xdp_get_frame_len(frame);
> >> >> xdp_return_frame(frame);
> >> >> }
> >> >> }
> >> >> + netdev_tx_completed_queue(txq, stats->napi_packets, stats->napi_bytes);
> >> >
> >> >Are you sure it's right? You are completing larger and larger
> >> >number of bytes and packets each time.
> >>
> >> Not sure I get you. __free_old_xmit() is always called with stats
> >> zeroed. So this is just sum-up of one queue completion run.
> >> I don't see how this could become "larger and larger number" as you
> >> describe.
> >
> >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.
> Perhaps a small comment in __free_old_xmit() would do better.
>
> One way or another, I think this is parallel to this patchset. Will
> handle it separatelly if you don't mind.
Okay.
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> >WDYT?
> >
> >>
> >> >
> >> >For example as won't this eventually trigger this inside dql_completed:
> >> >
> >> > BUG_ON(count > num_queued - dql->num_completed);
> >>
> >> Nope, I don't see how we can hit it. Do not complete anything else
> >> in addition to what was started in xmit(). Am I missing something?
> >>
> >>
> >> >
> >> >?
> >> >
> >> >
> >> >If I am right the perf testing has to be redone with this fixed ...
> >> >
> >> >
> >> >> }
> >> >>
> >>
> >> [...]
> >
