linux-kernel - Re: softirq under reporting with CONFIG_NO_HZ

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Date:	Mon, 11 May 2015 14:51:40 +0300
From:	Nikolay Borisov <kernel@...p.com>
To:	linux-kernel@...r.kernel.org
Subject: Re: softirq under reporting with CONFIG_NO_HZ_* and under syn flood
 ?

Hello

I can confirm that I'm also observing the same issue when running 
turbostat. I've attached the respective turbostat log with and without 
the hping syn flood running. I've also attached my kernel config.

It's evident that when the CPU is in c0 state (processing data) due to 
the syn packets the top utility doesn't detect it (for me it was showing 
sustained 0% usage both for kernel and user space)

Regards,
Nikolay

View attachment "kernel-conf" of type "text/plain" (93646 bytes)

View attachment "turbostat.log" of type "text/x-log" (3382 bytes)