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

From: Cong Wang
Date: Fri Mar 19 2021 - 15:46:17 EST

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.