[Linux-ia64] Re: Confused about fsystemcalls

David Mosberger
2003-01-30T04:39:56Z

>>>>> On Thu, 30 Jan 2003 15:31:19 +1100, Peter Chubb <peter@chubb.wattle.id.au> said:

Peter> Worked it out -- one needs to call the mygetpid() function
Peter> twice, once before the timing stuff, and once during, so we
Peter> don't count the time to get the gate page into the TLB and
Peter> into the cache.

Yes, that makes a big difference. Here is what I see for getppid() on
a McKinley:

getppid cycles: 1410 79 56 54 54 54 54 54 54 54

(I just added getppid() and I also added code to patch over the
McKinley E9 workaround on CPUs that don't need it.)

Peter> Timings are now 177 cycles for the mygetpid() routine as
Peter> opposed to 570 for glibc (all on Itanium 1),

Ah, that's much better.

Peter> and we're now working on gettimeofday().

Cool. I assume you're doing this based on the lock-free version that
Andrew Morton has in his latest patch?

--david