[Linux-ia64] Re: Confused about fsystemcalls

From: David Mosberger <davidm_at_napali.hpl.hp.com>
Date: 2003-01-30 15:39:56
>>>>> 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
Received on Wed Jan 29 20:41:41 2003

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