From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 9248F1007D4 for ; Fri, 2 Jul 2010 15:47:32 +1000 (EST) Subject: Re: CONFIG_NO_HZ causing poor console responsiveness From: Benjamin Herrenschmidt To: Timur Tabi In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Date: Fri, 02 Jul 2010 15:47:24 +1000 Message-ID: <1278049644.4200.377.camel@pasglop> Mime-Version: 1.0 Cc: Linuxppc-dev Development List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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. Cheers, Ben.