From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Wed, 02 Jun 2004 17:33:39 +0000 Subject: Re: Scalability enhancements for gettimeofday Message-Id: <16574.3955.332701.713217@napali.hpl.hp.com> List-Id: References: <200405201205.57930.clameter@sgi.com> In-Reply-To: <200405201205.57930.clameter@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org >>>>> On Thu, 20 May 2004 12:05:57 -0700, Christoph Lameter said: Christoph> The Altix systems never use ITC to determine the time so Christoph> this check and the cmpxchg is not necessary. I see the problem: the basic problem seems to come from the fact that the non-ITC-interpolation code didn't quite come out the way I anticipated: I expected even this code to use/need last_nsec_offset just like the ITC-based code, but it ended up not doing that. I _think_ that's OK and, if so, we should probably push all the last_nsec_offset back down into the interpolator-specific code. However, this is tricky code so I want to mull it some more to make sure I'm not missing a subtle race. Christoph> Also the fast system call handler for sys_gettimeofday() Christoph> can only improve scalability if the ITC is the basis for Christoph> gettimeofday which is also never the case on Altix SN2 Christoph> systems. Does this really make a substantial difference? My guess is no and, if so, I'd rather not add any more #ifdefs. --david