From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Mon, 12 Jul 2004 23:48:48 +0000 Subject: Re: Timer patches (nsec support + fastcalls for gettod/clock_gettime Message-Id: <16627.9056.572246.317538@napali.hpl.hp.com> 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 >>>>> On Mon, 12 Jul 2004 16:40:13 -0700 (PDT), Christoph Lameter said: Christoph> Ok. Will do all of what you said that I did not quote. Do Christoph> I really need to save predicates? There are no docs on Christoph> saving pr and the old gettimeofday assembly routine did Christoph> not save the predicates and worked without a problem. Preserved registers _always_ need to be preserved by fsys-handlers. If you avoid using preserved predicates, there is no need to save them. See the software conventions & runtime architecture guide for details (as far as predicate registers go, p1-p5 and p16-p63 are "preserved"). Christoph> I was not able to find the patch but I will talk to Christoph> George about this. However, gettimeofday with a timeval Christoph> is an established standard. George's current patches on Christoph> sf.net use clock_gettime to retrieve higher precision Christoph> timer values. The kernel-internal gettimeofday() can return anything it wants (as long as all platforms do it consistently. As to whether or not that's a good idea, i don't really care (but I do not think it's reasonable or necessary to have two platform routines with the only difference being whether they return timeval or timespec). Christoph> What could be done is to change do_gettimeofday to use a Christoph> timespec and then have sys_gettimeofday to the proper Christoph> scaling. Is that what you were thinking? Yup, that's what I meant. Christoph> But do_gettimeofday is used a gazillion times all over Christoph> the linux sources and changing that would result in a Christoph> huge patch that might not be acceptable either. That can be OK, if there is agreement that it's The Right Thing. Hence it's definitely something that should be done in coordination with George and lkml in general (and it also needs to be done separately from the ia64-specific changes; figuring out how to break the patch up is one thing we'll need to sort out eventually). --david