From owner-freebsd-questions Thu Apr 19 11:24: 5 2001 Delivered-To: freebsd-questions@freebsd.org Received: from hotmail.com (f180.law11.hotmail.com [64.4.17.180]) by hub.freebsd.org (Postfix) with ESMTP id 49A7837B42C for ; Thu, 19 Apr 2001 11:24:02 -0700 (PDT) (envelope-from burnscharlesn@hotmail.com) Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Thu, 19 Apr 2001 11:24:02 -0700 Received: from 64.20.170.140 by lw11fd.law11.hotmail.msn.com with HTTP; Thu, 19 Apr 2001 18:23:56 GMT X-Originating-IP: [64.20.170.140] From: "Charles Burns" To: jgowdy@home.com, vince@oahu.WURLDLINK.NET Cc: lplist@closedsrc.org, kris@obsecurity.org, mwlist@lanfear.com, freebsd@sysmach.com?, questions@FreeBSD.ORG Subject: Re: the AMD factor in FreeBSD Date: Thu, 19 Apr 2001 11:23:56 -0700 Mime-Version: 1.0 Content-Type: text/plain; format=flowed Message-ID: X-OriginalArrivalTime: 19 Apr 2001 18:24:02.0017 (UTC) FILETIME=[E88C6510:01C0C8FD] Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > > > The only significant performance advantage that the Pentium 3 has over >the > > > Athlon is that its l2 cache memory is _much_ faster than that of the >Athlon. > >Could you explain this ? If you're comparing Thunderbirds to Coppermines, >I >didn't think that was the case. Yes, I was comparing Coppermines with Thunderbirds. This is one of the reasons that the P3e is often very close to as fast as the Athlon at the same speed. Quick chart: Athlon T-bird P3e L1 cache 128K 32k L2 cache 256K 256k Total usable cache* 384K 256K L2 cache clockspeed** CPU core clock CPU core clock L2 cache BUS WIDTH** 64-bit 256-bit L2 bandwidth @ 1GHz 8GB/sec 32GB/sec *The P3 keeps a copy of L1 cache in the L2 cache, reducing the effective usable cache memory. **The first P3's had a 64-bit L2 cache running at 1/2 core clockspeed. The first Athlons had a 64-bit L2 cache running from 1/2 to 2/5 core clockspeed, depending on the speed of the Athlon. These were the Athlon "classics" as opposed to the "Thunderbirds". Both the original P3 and the original Athlon had 512K of L2 cache (twice as much), but this was too expensive to impliment when the moved the cache to the CPU core itself, so they eliminated some of it. The P3 Xeons have up to 4 megs of L2 cache. >In business applications benchmarks the Athlon always stomps the P3. I have seen this myself on systems that I have tested (even with the slightly better Intel chipsets) >If I remember correctly, depending on the type the best SDRAM gets about >800 >megs/sec. DDR SDRAM comes in two flavors, 1.6 gigs/sec and 2.1gigs/sec. Yep, the bandwidth can be calculated with the simple equation: [(Bus width)*(memory clock speed)*(1 if regular RAM, 2 if DDR RAM)] / (8*1024*1024) = MB/sec Or something like that. There are other things to consider like CAS latency, CAS-to-RAS latency and other latencies which I can't remember at the moment and the chipset and stuff. DDR is, as you said, certainly much faster overall. Please let me know if I screwed anything up. ;-) _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message