AMD64 Dual core

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jshriver
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AMD64 Dual core

Post by jshriver » Sun May 20, 2007 9:56 pm

Greetings,

Was curious, when AMD says a CPU is a 2 or 3ghz Dual core, does that mean each core is that speed or combined? Thought that was the truth, but noticed on my machine at work when I check /proc/cpuinfo it's actually 2 1ghz cores for a 2ghz AMD64.

Maybe linux is interpretting it wrong, or the ghz rating is really the combined rating of both cores. if this is true, then it would be better to buy a 3ghz CPU over 2 1.5 ghz cores, since you wouldnt have to worry about syncing and SMP issues.

Just curious.
-Josh

bob
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Re: AMD64 Dual core

Post by bob » Mon May 21, 2007 12:34 am

jshriver wrote:Greetings,

Was curious, when AMD says a CPU is a 2 or 3ghz Dual core, does that mean each core is that speed or combined? Thought that was the truth, but noticed on my machine at work when I check /proc/cpuinfo it's actually 2 1ghz cores for a 2ghz AMD64.

Maybe linux is interpretting it wrong, or the ghz rating is really the combined rating of both cores. if this is true, then it would be better to buy a 3ghz CPU over 2 1.5 ghz cores, since you wouldnt have to worry about syncing and SMP issues.

Just curious.
-Josh
That's the speed of each core. if you get a 3ghz dual core, each cpu core runs at 3.0ghz...

As far as your /proc/cpuinfo, that looks wrong. You might be running the thing where cpu throttling is used, which cuts the clock speed by 50% when that specific cpu is not busy. My 2.0ghz core2 duo always reports 1.0ghz unless I first crank up crafty. Then looking at /proc/cpuinfo shows each cpu running at 2.0ghz...

Nid Hogge

Re: AMD64 Dual core

Post by Nid Hogge » Mon May 21, 2007 5:21 pm

Yes, nothing to worry about.

In AMD CPU's It's a technology called Cool'n'Quiet. It works by reducing the processors clock rate and voltage when the computer has low utilization. It's automatically goes up when need it.

If I'm not mistaken you can disable it from the BIOS. Then it works 100% all the time, But I wouldn't recommend doing that.

In Intel CPU's there's a similar feature as well called SpeedStep(EIST).

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