linux-kernel - Re: [PATCH linux-next] net: record times of netdev

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Message-ID: <20221207153256.6c0ec51a@kernel.org>
Date:   Wed, 7 Dec 2022 15:32:56 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     <yang.yang29@....com.cn>
Cc:     <edumazet@...gle.com>, <davem@...emloft.net>, <pabeni@...hat.com>,
        <bigeasy@...utronix.de>, <imagedong@...cent.com>,
        <kuniyu@...zon.com>, <petrm@...dia.com>, <liu3101@...due.edu>,
        <wujianguo@...natelecom.cn>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <tedheadster@...il.com>
Subject: Re: [PATCH linux-next] net: record times of netdev_budget exhausted

On Wed, 7 Dec 2022 20:30:08 +0800 (CST) yang.yang29@....com.cn wrote:
> > Presumably, modern tracing techniques can let you do what you want
> > without adding new counters.  
> 
> By the way, should we add a tracepoint likes trace_napi_poll() to make
> it easier? Something likes:
>         if (unlikely(budget <= 0 ||
>                  time_after_eq(jiffies, time_limit))) {
>             sd->time_squeeze++;
> +            trace_napi_poll(budget, jiffies, time_limit);
>             break;
>         }

In my experience - no this is not useful.

Sorry if this is too direct, but it seems to me like you're trying hard
to find something useful to do in this area without a clear use case. 
We have coding tasks which would definitely be useful and which nobody
has time to accomplish. Please ask if you're trying to find something
to do.