Subject: Re: packet re-ordering on SMP machines.

From: "Xiaoliang \(David\) Wei" <[email-masked]>
Date: Tue, 27 Aug 2002 12:43:02 -0700

> >
> > That is because of the lock it takes. Locks are always slow.
>
> xtime_lock?
I guess so, after looked at do_gettimeofday

>
> > Possibilities:
> >
> > - Ignore the problem and switch back to gettimeoffset again
>
> Is it safe to call gettimeoffset without the lock?
What's the possible danger to ignore the lock? Can I read the xtime
directly?

>
> > - Switch to gettimeoffset but add some correction step for the unlikely
> > case that someone wants the timestamp from user space
> > (would be my prefered solution)
> > - Implement lockless gettimeofday like x86-64 or sparc
> > (good one too, but likely slower than last)
>
>
> ia64 seems to also have the lock.
>
> cheers,
> jamal
>
>
>
>