Date: Mon, 5 Mar 2001 12:27:20 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: Chris Dillon <cdillon@wolves.k12.mo.us> Cc: "E.B. Dreger" <eddy+public+spam@noc.everquick.net>, <freebsd-hackers@FreeBSD.ORG> Subject: Re: Machines are getting too damn fast Message-ID: <200103052027.f25KRK442804@earth.backplane.com> References: <Pine.BSF.4.32.0103050855460.72733-100000@mail.wolves.k12.mo.us>
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:On Mon, 5 Mar 2001, E.B. Dreger wrote:
:
:I've got a ServerWorks III HE-SL system with 512MB of two-way
:interleaved PC133 SDRAM and dual PIII-800's. Is that close enough?
::-)
:
:Here is my "memory bandwidth test", much much simpler and less
:scientific than Matt's:
:
:dd if=/dev/zero of=/dev/null bs=10m count=1000
:1000+0 records in
:1000+0 records out
:10485760000 bytes transferred in 23.716504 secs (442129245 bytes/sec)
:
:I just did a recent 4.2-STABLE 'make -j 4 buildworld' on that system
:in just over 34 minutes. Here's the time output:
:1980.707u 768.223s 34:20.89 133.3% 1297+1456k 39517+6202io 1661pf+0w
That is quite impressive for SDRAM, though I'm not exactly sure what's
being measured due to the way /dev/zero and /dev/null operate. On
my system the above dd test returns around 883MB/sec so I would guess
that it is only doing a read-swipe on the memory.
(sony 1.3G / RIMM)
apollo:/home/dillon> dd if=/dev/zero of=/dev/null bs=10m count=1000
1000+0 records in
1000+0 records out
10485760000 bytes transferred in 11.867550 secs (883565697 bytes/sec)
On the DELL 2400 I get:
1048576000 bytes transferred in 2.737955 secs (382977810 bytes/sec)
The only thing I don't like about this baby is the IBM IDE hard drive's
write performance. I only get 10-12 MBytes/sec. Read performance is
incredible, though... I get 37MB/sec dd'ing from /dev/ad0s1a to
/dev/null.
ad0: 58644MB <IBM-DTLA-307060> [119150/16/63] at ata0-master UDMA100
-Matt
:> If one _truly_ needs the bandwidth of Rambus (which, IIRC, is
:> higher real-world latency than SDRAM), then how about having the
:> bus bandwidth to back it up?
:
:The higher real-world latency of RDRAM over SDRAM is what makes the
:benefits of its higher bandwidth so questionable. PC2100 DDR-SDRAM --
:which has higher latencies than regular SDRAM but still lower than
:RDRAM -- should have it beat soundly, though we'll have to wait for
:some systems that are actually designed to take advantage of it to say
:for sure. :-)
:
:
:-- Chris Dillon - cdillon@wolves.k12.mo.us - cdillon@inter-linc.net
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