From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from imap.sh.mvista.com (unknown [63.81.120.155]) by ozlabs.org (Postfix) with ESMTP id 1CF36DDEE0 for ; Sat, 19 May 2007 00:51:12 +1000 (EST) Message-ID: <464DBDBA.3060801@ru.mvista.com> Date: Fri, 18 May 2007 18:52:42 +0400 From: Sergei Shtylyov MIME-Version: 1.0 To: Albert Cahalan Subject: Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver References: <787b0d920705172024g723412b4n8f82d3cd78e0f702@mail.gmail.com> In-Reply-To: <787b0d920705172024g723412b4n8f82d3cd78e0f702@mail.gmail.com> Content-Type: text/plain; charset=us-ascii; format=flowed Cc: linuxppc-dev@ozlabs.org, tglx@linutronix.de, linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hello. Albert Cahalan wrote: >>>>> I haven't looked at all the new clock/timer code, is there any >>>>> utility in having support for more than one clock source? >>>> Of course, you may register as many as you like. >>> Sure, but is there any utility in registering more than the >>> decrementer on PPC? >> Not yet. I'm not sure I know any other PPC CPU facility fitting >> for clockevents. In theory, FIT could be used -- but its period >> is measured in powers of 2, IIRC. > I'd really like to have that as an option. It would allow oprofile > to safely use hardware events on the MPC74xx "G4" processors. > Alternately it would allow thermal events. It is safe to use at > most one of the three (decrementer,profiling,thermal) interrupts. > If two were to hit at the same time, badness happens. Unfortunately, FIT exists only on Book E CPUs and MPC74xx aren't Book E, IIUC. > It's possible to wrapper the interrupt in something that divides > down, calling the normal code only some of the time. I think one > of the FIT choices is about 4 kHz on my system, which would be OK. Erm, are you sure you have FIT (or is your system not MPC74xx based)? > Full oprofile functionality would be wonderful. WBR, Sergei