CONFIG_NO_HZ causing poor console responsiveness

Li Yang-R58472 r58472 at
Fri Jul 2 16:03:53 EST 2010

>-----Original Message-----
>From: at
>[ at] On
>Behalf Of Benjamin Herrenschmidt
>Sent: Friday, July 02, 2010 1:47 PM
>To: Tabi Timur-B04825
>Cc: Linuxppc-dev Development
>Subject: Re: CONFIG_NO_HZ causing poor console responsiveness
>On Tue, 2010-06-29 at 14:54 -0500, Timur Tabi wrote:
>> I'm adding support for a new e500-based board (the P1022DS), and in
>> the process I've discovered that enabling CONFIG_NO_HZ (Tickless
>> System / Dynamic Ticks) causes significant responsiveness problems on
>> the serial console.  When I type on the console, I see delays of up to
>> a half-second for almost every character.  It acts as if there's a
>> background process eating all the CPU.
>> I don't have time to debug this thoroughly at the moment.  The problem
>> occurs in the latest kernel, but it appears not to occur in 2.6.32.
>> Has anyone else seen anything like this?
>I noticed that on the bimini with 2.6.35-rc* though I didn't get to track
>it down yet.

Patch found at the following location fixed this problem.

Hope it has already been merged.

- Leo

More information about the Linuxppc-dev mailing list