From: Jakub Kicinski <kuba@kernel.org>
To: Yunsheng Lin <linyunsheng@huawei.com>
Cc: <davem@davemloft.net>, <olteanv@gmail.com>, <ast@kernel.org>,
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Subject: Re: [Linuxarm] Re: [PATCH net v6 3/3] net: sched: fix tx action reschedule issue with stopped queue
Date: Wed, 12 May 2021 12:47:31 -0700 [thread overview]
Message-ID: <20210512124731.2993dac7@kicinski-fedora-PC1C0HJN> (raw)
In-Reply-To: <62054a31-4708-1696-60d5-b33e4993cddc@huawei.com>
On Wed, 12 May 2021 11:34:55 +0800 Yunsheng Lin wrote:
> > This is indeed the idiomatic way of dealing with Tx queue stopping race,
> > but it's a bit of code to sprinkle around. My vote would be option 1.
>
> I had done some performance testing to see which is better, tested using
> pktgen and dummy netdev with pfifo_fast qdisc attached:
>
> unit: Mpps
>
> threads V6 V6 + option 1 V6 + option 3
> 1 2.60 2.54 2.60
> 2 3.86 3.84 3.84
> 4 5.56 5.50 5.51
> 8 2.79 2.77 2.77
> 16 2.23 2.24 2.22
>
> So it seems the netif_xmit_frozen_or_stopped checking overhead for non-stopped queue
> is noticable for 1 pktgen thread.
>
> And the performance increase for V6 + option 1 with 16 pktgen threads is because of
> "clear_bit(__QDISC_STATE_MISSED, &qdisc->state)" at the end of qdisc_run_end(), which
> may avoid the another round of dequeuing in the pfifo_fast_dequeue(). And adding the
> "clear_bit(__QDISC_STATE_MISSED, &qdisc->state)" for V6 + option 3, the data for
> 16 pktgen thread also go up to 2.24Mpps.
>
>
> So it seems V6 + option 3 with "clear_bit(__QDISC_STATE_MISSED, &qdisc->state)" at
> the end of qdisc_run_end() is better?
Alright, sounds good.
prev parent reply other threads:[~2021-05-12 20:34 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-10 1:42 [PATCH net v6 0/3] fix packet stuck problem for lockless qdisc Yunsheng Lin
2021-05-10 1:42 ` [PATCH net v6 1/3] net: sched: " Yunsheng Lin
2021-05-10 1:42 ` [PATCH net v6 2/3] net: sched: fix endless tx action reschedule during deactivation Yunsheng Lin
2021-05-10 1:42 ` [PATCH net v6 3/3] net: sched: fix tx action reschedule issue with stopped queue Yunsheng Lin
2021-05-11 4:22 ` Jakub Kicinski
2021-05-11 9:04 ` Yunsheng Lin
2021-05-11 12:13 ` Yunsheng Lin
2021-05-11 23:30 ` Jakub Kicinski
2021-05-12 3:34 ` [Linuxarm] " Yunsheng Lin
2021-05-12 19:47 ` Jakub Kicinski [this message]
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