From mboxrd@z Thu Jan 1 00:00:00 1970 From: john stultz Date: Tue, 18 Nov 2003 01:02:55 +0000 Subject: Re: [RFC][PATCH] linux-2.4.23-pre9_ia64-cyclone_A0 Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org [Resent to the proper mailing list] On Mon, 2003-11-17 at 16:23, Bjorn Helgaas wrote: > On Friday 14 November 2003 6:24 pm, john stultz wrote: > > This patch was developed for the distros to support the cyclone time > > source on IBM x455 systems. x455 systems are multi-node NUMA systems > > which suffer from unsynced ITCs, which can cause non-monotonically > > increasing results from gettimeofday(). Very similar code was > > implemented in the i386 arch to resolve the same issue on x440s. > > ... > > Any comments or feedback would be appreciated. > > There's a generic infrastructure for this in 2.5: > http://linux.bkbits.net:8080/linux-2.5/cset@1.1046.203.22?nav=index.html|src/.|src/include|src/include/linux|related/include/linux/timex.h Yep, I'm looking at exactly that for my 2.5 patch. But thanks for the pointer. > SGI uses a similar design in 2.4, but apparently there are some > issues with it: > http://www.gelato.unsw.edu.au/linux-ia64/0310/6973.html > > I'd like to see those issues resolved and the Cyclone support > put into the same framework as the SGI work. Hmmm. I think I've grasped the issue there. It seems the problem is not calculating the equivalent of delay_at_last_interrupt found in the i386 time code. I'll see if I cannot come up with something similar. Also I'd definitely like to share more infrastructure w/ the SN2 folks, is there a pointer to their 2.4 gettimeoffset() patch around? thanks -john