From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Gonzalez-Sigler Date: Mon, 12 Jul 2004 12:01:15 +0000 Subject: Re: Consistency problem on IPF Message-Id: <40F27D8B.6010202@inria.fr> List-Id: References: <40F2562C.10208@inria.fr> In-Reply-To: <40F2562C.10208@inria.fr> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Erich Focht wrote: > On Monday 12 July 2004 13:12, Duraid Madina wrote: > >> For the record, on HP-UX 11.23 the standard deviation is down around >> 0.1s for NP0, 512. For N24, it's basically zero. This is on a 2-way >> 1.5G/6M system. > > Which page-size was the testcode using? HPUX is more flexible here due > to different usage of the TLB. > > What compiler? The initial mail sounded like gcc has been used. I'd > expect a reasonable (i.e. optimizing) compiler to recognize the > trivial matrix-matrix multiply pattern and replace it by highly > optimized code. Which would reduce the problems... (For the record, I tried gcc-3.3.4 and orcc-2.1) Perhaps I was not clear enough. I used matrix-matrix multiply only as an example. My real problem is the non-deterministic behavior. Say I tile the main loop nest. I want to compare the execution time of the original, untiled program and the execution time of the modified, tiled program. If the original version completes in 1 second 80% of the time, and the modified version completes in 0.5 seconds 80% of the time, but 2 seconds 20% of the time, then, if I am unlucky, I might eliminate an excellent candidate. This is why I need the execution times of a given program to be consistent. I have looked at /usr/src/linux/Documentation/vm/hugetlbpage.txt and I will try it if there are no better solutions. -- Regards, Marc