Re: [Linuxarm] [PATCH net] net: sched: fix packet stuck problem for lockless qdisc

[Cong Wang]

On Fri, Mar 19, 2021 at 2:25 AM Yunsheng Lin <linyunsheng@xxxxxxxxxx> wrote:
> I had done some performance test to see if there is value to
> fix the packet stuck problem and support lockless qdisc bypass,
> here is some result using pktgen in 'queue_xmit' mode on a dummy
> device as Paolo Abeni had done in [1], and using pfifo_fast qdisc:
>
> threads  vanilla    locked-qdisc    vanilla+this_patch
>    1     2.6Mpps      2.9Mpps            2.5Mpps
>    2     3.9Mpps      4.8Mpps            3.6Mpps
>    4     5.6Mpps      3.0Mpps            4.7Mpps
>    8     2.7Mpps      1.6Mpps            2.8Mpps
>    16    2.2Mpps      1.3Mpps            2.3Mpps
>
> locked-qdisc: test by removing the "TCQ_F_NOLOCK | TCQ_F_CPUSTATS".

I read this as this patch introduces somehow a performance
regression for -net, as the lockless bypass patch you submitted is
for -net-next.

Thanks.