From: Eric Dumazet <eric.dumazet@gmail.com>
To: Peter Hurley <peter@hurleysoftware.com>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>,
Francois Romieu <romieu@fr.zoreil.com>,
Eric Dumazet <edumazet@google.com>,
David Miller <davem@davemloft.net>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Greg KH <gregkh@linuxfoundation.org>,
dmaengine@vger.kernel.org,
John Ogness <john.ogness@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: Softirq priority inversion from "softirq: reduce latencies"
Date: Mon, 29 Feb 2016 10:24:39 -0800 [thread overview]
Message-ID: <1456770279.648.85.camel@edumazet-ThinkPad-T530> (raw)
In-Reply-To: <56D48869.1000106@hurleysoftware.com>
On lun., 2016-02-29 at 10:05 -0800, Peter Hurley wrote:
> While I appreciate the attempt, that's not the problem.
>
> Just to be clear
>
> if (time_before(jiffies, end) && !need_resched() &&
> --max_restart)
> goto restart;
>
> aborts softirq *even if 0ns have elapsed*, if NET_RX has woken a process.
Sure, now remove the 1st and 2nd condition.
You would still 'abort' (ie wakeup ksoftirqd really) when --max_restart
becomes 0
So, instead of some subtle load dependent bug, you know have a reliable
trigger.
The fact it took 3 years for someone to complain about this change
should tell us something really.
The only way for your bug to hide would be to remove all the 'break
infinite loop' logic.
And this is not going to happen.
next prev parent reply other threads:[~2016-02-29 18:25 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-27 18:19 Softirq priority inversion from "softirq: reduce latencies" Peter Hurley
2016-02-27 20:13 ` Eric Dumazet
2016-02-27 20:29 ` Peter Hurley
2016-02-27 23:04 ` David Miller
2016-02-27 23:33 ` Peter Hurley
2016-02-28 1:59 ` Eric Dumazet
2016-02-28 2:10 ` Peter Hurley
2016-02-28 2:17 ` Eric Dumazet
2016-02-28 4:46 ` David Miller
2016-02-28 5:55 ` Mike Galbraith
2016-02-28 17:01 ` Francois Romieu
2016-02-29 4:58 ` Mike Galbraith
2016-02-29 15:03 ` Peter Hurley
2016-02-29 15:19 ` Eric Dumazet
2016-02-29 15:54 ` Peter Hurley
2016-02-29 16:21 ` Eric Dumazet
2016-02-29 18:05 ` Peter Hurley
2016-02-29 18:24 ` Eric Dumazet [this message]
2016-02-29 18:53 ` Peter Hurley
2016-02-29 19:14 ` Thomas Gleixner
2016-02-29 20:24 ` David Miller
2016-02-29 23:04 ` Peter Hurley
2016-02-29 15:27 ` Eric Dumazet
2016-02-29 19:13 ` Peter Hurley
2016-02-29 19:43 ` Eric Dumazet
2016-02-29 15:40 ` Mike Galbraith
2016-02-29 15:58 ` Peter Hurley
2016-02-29 16:24 ` Eric Dumazet
2016-02-29 17:16 ` David Miller
2016-03-07 15:31 ` Sebastian Andrzej Siewior
2016-03-07 17:06 ` Mike Galbraith
2016-03-07 15:48 ` Sebastian Andrzej Siewior
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