netdev - Re: [PATCH net-next v4 11/11] bpf: add simple bpf tests in the tx path for so

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Message-ID: <CAL+tcoDW744G+V1zGSThAT6h1gSeBAV5MdEZOBeXE+8xAPovVQ@mail.gmail.com>
Date: Sat, 14 Dec 2024 08:45:41 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Martin KaFai Lau <martin.lau@...ux.dev>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, 
	pabeni@...hat.com, dsahern@...nel.org, willemdebruijn.kernel@...il.com, 
	willemb@...gle.com, ast@...nel.org, daniel@...earbox.net, andrii@...nel.org, 
	eddyz87@...il.com, song@...nel.org, yonghong.song@...ux.dev, 
	john.fastabend@...il.com, kpsingh@...nel.org, sdf@...ichev.me, 
	haoluo@...gle.com, jolsa@...nel.org, bpf@...r.kernel.org, 
	netdev@...r.kernel.org, Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next v4 11/11] bpf: add simple bpf tests in the tx
 path for so_timstamping feature

On Sat, Dec 14, 2024 at 8:14 AM Martin KaFai Lau <martin.lau@...ux.dev> wrote:
>
> On 12/13/24 8:02 AM, Jason Xing wrote:
> >>> +static u64 delay_tolerance_nsec = 5000000;
> >>
> >> If I count right, 5ms may not a lot for the bpf CI and the test could become
> >> flaky. Probably good enough to ensure the delay is larger than the previous one.
> >
> > You're right, initially I set 2ms which make the test flaky. How about
> > 20ms? We cannot ensure each delta (calculated between two tx points)
> > is larger than the previous one.
>
> or I was thinking the delay is always measured from sendmsg_ns.
>
> Regardless, whatever way the delay of a tx point is measured from (always from
> sendmsg_ns or from the previous tx point), it can also just check the measured
> delay is +ve or something like that instead of having a hard coded maximum delay
> here.

That makes things simpler. Got it.

>
> The following "struct delay_info" may not be the best. Feel free to adjust.

Okay.

>
> >> struct delay_info {
> >>          u64 sendmsg_ns;
> >>          u32 sched_delay;  /* SCHED_OPT_CB - sendmsg_ns */
> >>          u32 sw_snd_delay;
> >>          u32 ack_delay;
> >> };
>