linux-kernel - Re: [PATCHv6 0/2] *** Detect interrupt storm in softlockup ***

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Date: Sun, 11 Feb 2024 23:36:37 +0800
From: Bitao Hu <yaoma@...ux.alibaba.com>
To: Petr Mladek <pmladek@...e.com>
Cc: dianders@...omium.org, akpm@...ux-foundation.org, kernelfans@...il.com,
 liusong@...ux.alibaba.com, linux-kernel@...r.kernel.org,
 yaoma@...ux.alibaba.com
Subject: Re: [PATCHv6 0/2] *** Detect interrupt storm in softlockup ***



On 2024/2/9 22:48, Petr Mladek wrote:
> On Thu 2024-02-08 20:54:24, Bitao Hu wrote:
>> Hi, guys.
>> I have implemented a low-overhead method for detecting interrupt
>> storm in softlockup. Please review it, all comments are welcome.
> 
> I like this work.
> 
> I wonder if you might be interested also in reporting problems
> when soft IRQs are offloaded to the "ksoftirqd/X" kthreads
> for too long.
> 
> The kthreads are processes with normal priority. As a result,
> offloading soft IRQs to kthreads might cause huge difference
> on loaded systems.
> 
> I have seen several problems when a flood of softIRQs triggered
> offloading them. And it caused several second delays on networking
> interfaces.
> 
This is an interesting issue! I had considered the matter of softirq
while working on this, but since there were no actual issues at hand,
I didn't conduct an analysis. Your mention of this problem has
opened my eyes.

Best Regards,
Bitao