From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (from majordomo@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id XAA05713; Fri, 13 Jun 2003 23:05:29 +0200 (MET DST) X-Authentication-Warning: pauillac.inria.fr: majordomo set sender to owner-caml-list@pauillac.inria.fr using -f Received: from concorde.inria.fr (concorde.inria.fr [192.93.2.39]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id XAA05608 for ; Fri, 13 Jun 2003 23:05:28 +0200 (MET DST) Received: from bluejay.mail.pas.earthlink.net (bluejay.mail.pas.earthlink.net [207.217.120.218]) by concorde.inria.fr (8.11.1/8.11.1) with ESMTP id h5DL5RH02222 for ; Fri, 13 Jun 2003 23:05:27 +0200 (MET DST) Received: from tcsndslgw9poolf147.tcsn.uswest.net ([67.41.20.147] helo=dylan) by bluejay.mail.pas.earthlink.net with asmtp (Exim 3.33 #1) id 19Qvjg-0000Tw-00 for caml-list@inria.fr; Fri, 13 Jun 2003 14:05:24 -0700 Message-ID: <009d01c331ef$9642c990$0201a8c0@dylan> From: "David McClain" To: Subject: [Caml-list] Hyperthreading Date: Fri, 13 Jun 2003 14:05:56 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 X-ELNK-Trace: 7a0ab3eafc8cf994b22988ad1c62733440683398e744b8a4fce60edd3c450c67ed96ec3702d5382b350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Spam: no; 0.00; mcclain:01 dmcclain:01 consumed:01 locality:01 shifts:01 high-level:01 arrays:01 caml:01 mainstream:01 ought:01 address:96 computations:03 rates:96 data:03 cycles:04 Sender: owner-caml-list@pauillac.inria.fr Precedence: bulk > How do you measure "CPU utilization"? Different tools have different I just used the simple minded task manager graphs. I don't have those details just yet, but I do have the Intel VTune tools to do a serious look at what's happening inside the CPU. Another possibility occured to me, but it would mimmick the low CPU utilization we get. But on the newer processors, instruction ordering may have an impact on the speed of execution. I have some other 3rd party tools here that appear to be using enormous amounts of CPU cycles for apparently simple computations. But these tools are intended to run on a wide variety of Pentium platforms, and they were definitely not especially compiled for the P4. > > My general feeling (although I have no proof of that) is that the > memory usage patterns of Caml programs aren't radically different from > those of more mainstream programs. You may well be correct about this... but then, how many programs take care to tune the pattern of memory use? In my own numerical code, I know that enormous floating-point arrays are being consumed and produced at prodigious rates. The need to have better data locality never showed itself before on those older processors. But clearly, speeding up the CPU by a factor of 10 to reach an overall throughput improvement of only a factor of 2, points to inefficiencies that I now ought to address. But ulimately, it would be much nicer if some hardware guru's could get better educated on the nature of high level languages, and stop thinking that everything is written in hand-crafted C code. We need some paradigm shifts in the way processors attack high-level programs. Cheers, - DM ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners