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Author Topic: Looking at Three Systems (poor hash rates on a Xeon)  (Read 2177 times)
inertia
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November 20, 2010, 09:18:26 PM
 #1

I didn't set any switches on the command line on any of these configuration.

System A: Xeon x4 @ 3.0GHz Windows 2003 Small Business Server (32-bit), Bitcoin v0.3.15:
Limited to 4 CPU: ~900 khash/s
Limited to 3 CPU: ~1100 khash/s
Limited to 2 CPU: ~1100 khash/s
Limited to 1 CPU: ~725 khash/s

System B: Core i7 x4 @2.66GHz Mac OS X 10.6.5 (64-bit), Bitcoin v0.3.13:
Limited to 4 CPU: ~1800 khash/s
Limited to 3 CPU: ~1800 khash/s
Limited to 2 CPU: ~1500 khash/s
Limited to 1 CPU: ~1000 khash/s

System C: Core i7 x4 @2.66 Windows XP x64 Edition (in VMWare Fusion on Mac OS X 10.6.5), Bitcoin v0.03.15:
Limited to 4 CPU: ~2100 khash/s
Limited to 3 CPU: ~2300 khash/s
Limited to 2 CPU: ~1900 khash/s
Limited to 1 CPU: ~1200 khash/s

I'm particularly concerned about System A.  How can 3 GHz only reach 900 khash/s?  I thought it was odd that limiting the number of CPUs to 3 allows the hash rate to increase.  That's why I looked at System B and C.  I wanted to see if the same thing would happen.

So System A doesn't scale in a way I would have expected.  If I get ~725 on one CPU, I would expect ~2900 on four.  But none of my configurations scale like that, so is this a reasonable expectation?  I would have never tried limiting any of my systems to 3 CPUs until I started monkeying with System A, trying to figure out why it was getting such poor hash rates.  Who would ever think to run 3 CPUs anyway?  If you intend to limit, you would probably limit to half, or a quarter, not three quarters.  It didn't occur to me to try it until today.

Systems B and C are actually the same computer.  Both configurations have managed to generate.  My theory as to why the virtualize System C is able to reach higher hash rates than the Mac OS X client is that VMWare is able to schedule as with system priorities as opposed to user priorities.

Anyway, my main question here is why does a 3.0 GHz system is getting such abismal hash rates as compared to the 2.66 GHz system?  Is Core i7 really that superior to Xeon?

You should try my Minecraft server.
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wumpus
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November 20, 2010, 09:35:51 PM
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Compared to the systems in this topic you get really low hash rates:
https://www.bitcoin.org/smf/index.php?topic=1628.0

I don't know why.

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inertia
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November 20, 2010, 09:38:40 PM
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Compared to the systems in this topic you get really low hash rates:
https://www.bitcoin.org/smf/index.php?topic=1628.0

I don't know why.


Indeed.  I saw that thread and tried -4way (and even -4way=0), but it didn't slow anything down nor speed it up.

You should try my Minecraft server.
theymos
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November 20, 2010, 09:52:22 PM
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It sounds like you actually only have two physical cores, and you're including the virtual hyper-threading cores. This has different effects on different architectures.

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November 20, 2010, 10:05:25 PM
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The Xeon brand stands for a huge range of different CPUs, from the Pentium II days to present. Without a model number it is impossible to tell what kind of a processor it is. A 3.0 GHz Xeon could have a Pentium 4 architecture, which is not particularly efficient.

inertia
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November 20, 2010, 11:53:03 PM
 #6

It sounds like you actually only have two physical cores, and you're including the virtual hyper-threading cores. This has different effects on different architectures.

Ok, turns out Small Business Server limits the number of physical CPUs to two.  Hyperthreading was indeed enabled so a cursory view made it appear there were four CPUs.  Disabling hyperthreading brought the hash rate up to 1400 on two CPUs, which seems fairly appropriate.

You should try my Minecraft server.
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