netdev - Re: [PATCH bpf-next 0/6] xsk: exit NAPI loop when AF

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Message-ID: <20200904162751.632c4443@carbon>
Date:   Fri, 4 Sep 2020 16:27:51 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Björn Töpel <bjorn.topel@...il.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Cc:     brouer@...hat.com, ast@...nel.org, daniel@...earbox.net,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        magnus.karlsson@...el.com, bjorn.topel@...el.com,
        davem@...emloft.net, kuba@...nel.org, john.fastabend@...il.com,
        intel-wired-lan@...ts.osuosl.org
Subject: Re: [PATCH bpf-next 0/6] xsk: exit NAPI loop when AF_XDP Rx ring is
 full

On Fri,  4 Sep 2020 15:53:25 +0200
Björn Töpel <bjorn.topel@...il.com> wrote:

> On my machine the "one core scenario Rx drop" performance went from
> ~65Kpps to 21Mpps. In other words, from "not usable" to
> "usable". YMMV.

We have observed this kind of dropping off an edge before with softirq
(when userspace process runs on same RX-CPU), but I thought that Eric
Dumazet solved it in 4cd13c21b207 ("softirq: Let ksoftirqd do its job").

I wonder what makes AF_XDP different or if the problem have come back?

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer