Credit always low

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Profile Hammeh

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Message 65770 - Posted: 19 Apr 2010, 12:50:01 UTC

Hey!!

Lately, I have started my computers crunching Rosetta@home again.
However, after reviewing the completed tasks, I find that my main quad core computer is constantly being granted less credit than it is claiming whilst my dual core one is the opposite!

Is there any reason for this?
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Message 65771 - Posted: 19 Apr 2010, 13:44:53 UTC

The main difference is that your quad core is AMD, and your dual core is Intel (Core 2 duo). In my opinion. Your Intel is better suited for Rosetta and is therefore granting more credit, relatively. The Intel might be generating more models per task and for that reason the granted credit might be higher. The only reason the AMD has a higher RAC might be because it has twice as many cores.
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Message 65772 - Posted: 19 Apr 2010, 14:57:23 UTC

Looks like the Intel has a 2MB L2 cache as well, for 2 active processes. That is 4x larger then the AMD which is trying to run 4 active processes. Experience has shown that Rosetta workloads tend to run better when large L2 cache available. This is probably due to the relatively large program size.

Credit is based on actual models completed. There is some variation from task to task and model to model as to how many operations are required to complete a given model, so the numbers are really most meaningful when averaged over a period of time (which you seem to have done, I'm just trying to be specific for future readers).

Bottom line is that the raw CPU speed of the AMD is faster, and so the claims are high, but the actual ability to manage memory and complete work is not keeping up with the Intel. You are witnessing part of why it is very difficult to compare CPUs to one another. And why one vendor perfers to reference one benchmark while another vendor will always use another, some benchmarks run better with large L2 cache, others do more floating point operations then integer, etc.
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Message 65783 - Posted: 20 Apr 2010, 13:22:19 UTC - in response to Message 65771.  

The main difference is that your quad core is AMD, and your dual core is Intel (Core 2 duo). In my opinion. Your Intel is better suited for Rosetta and is therefore granting more credit, relatively. The Intel might be generating more models per task and for that reason the granted credit might be higher. The only reason the AMD has a higher RAC might be because it has twice as many cores.

I'm in exactly the same configuration and can confirm the same results. But the dual core Intel (2.2GHz) has a total RAC of ~750 and the quad core AMD ~1300 (2.5GHz), so it's significant but not especially so. In all other respects the W7 laptop is a pain while Vista desktop very smooth. Boinc is its saving grace.

It's all incidental to the results we're seeing here at Rosetta, especially right now.
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Message 65808 - Posted: 24 Apr 2010, 14:57:32 UTC

I have got the impression, that the granted credits are just based on the CPU-type. My i7 920@3.6 GHz is claiming ~70 credits and gets ~40 credits granted. I have looked up some non-oced i7 920, they are getting granted the same ~40 credits, although my machine is oced by 30 percent... Actually, this is the reason, why I don't use my i7 for Rosetta very much.

Joe
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Message 65809 - Posted: 24 Apr 2010, 20:19:18 UTC

My strongest machine (Intel T8300 OC'ed to 2.9GHz) get's an average of 54.4 credits per WU @ 2hr/WU.

It beats my strongest AMD machine (43.3), even tho it gets a lower benchmark rating than it.

I used 18 WUs as my pop.
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Message 65810 - Posted: 24 Apr 2010, 21:56:21 UTC - in response to Message 65808.  

I have got the impression, that the granted credits are just based on the CPU-type. My i7 920@3.6 GHz is claiming ~70 credits and gets ~40 credits granted. I have looked up some non-oced i7 920, they are getting granted the same ~40 credits, although my machine is oced by 30 percent... Actually, this is the reason, why I don't use my i7 for Rosetta very much.

Joe


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Message 65813 - Posted: 25 Apr 2010, 10:38:10 UTC - in response to Message 65808.  

I have got the impression, that the granted credits are just based on the CPU-type.


Well, that impression is wrong. Here's an explanation of the credit system:

https://boinc.bakerlab.org/rosetta/forum_thread.php?id=2194&nowrap=true#24612

The reason i7 and AMD CPU's appear to generate less credits is not because of how Granted Credit is calculated.
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Jochen

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Message 65814 - Posted: 25 Apr 2010, 11:25:26 UTC - in response to Message 65813.  

Credits are granted based on the actual work done and faster machines receive more credit than slower ones accordingly to their actual contribution.

Well, in this case, I do not understand, why my 920@3.6 does not get more credits than a 920@2.67?

Jochen

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Message 65816 - Posted: 25 Apr 2010, 13:40:58 UTC - in response to Message 65814.  

Credits are granted based on the actual work done and faster machines receive more credit than slower ones accordingly to their actual contribution.

Well, in this case, I do not understand, why my 920@3.6 does not get more credits than a 920@2.67?

Jochen


From the link below:
"Credit shall be granted by the actual work done from the host. In order to achieve that we grant credit based on the number of models (decoys) completed for each work unit. This relates exactly to the actual scientific contribution. For each type of WU we determine a credit/model ratio which we will grant as "work credit". A faster machine which completes more models in the same time will receive more credits."

Unfortunately credits cannot be compared directly to another machine over the short run, over the long term yes they can, but the long term may be weeks or even months. This has always been, and probably always be, a bone of contention but it is what it is. There are other variables too, do you crunch for other projects? Is a hard drive failing on one machine and writing slowly? Is one piece of ram in one machine flaky? Waaay too many variables involved from machine to machine, and we haven't even talked about the different units that get crunched. A very long time ago a standard unit for crunching was discussed, and thrown out, that would have been sent to every machine that would set the standard for what credits that machine gets. It was thrown out because the Developers thought people wanted to get credit from crunching, not running the same old unit week after week after week.
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Jochen

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Message 65817 - Posted: 25 Apr 2010, 14:18:03 UTC

I had this rig running Rosetta for at least 3 months last year... I would consider this a long term. My rig is claiming the correct amount of credits, but just gets granted, what the same CPU@stock-clock is granted.
It looks like, there is a table with CPU-types and WU-types to look up the granted credit - and this does not take oced rigs into consideration.

I am sorry for my poor english, I can not explain it any better.

Jochen
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Message 65823 - Posted: 25 Apr 2010, 18:46:15 UTC - in response to Message 65817.  

I had this rig running Rosetta for at least 3 months last year... I would consider this a long term. My rig is claiming the correct amount of credits, but just gets granted, what the same CPU@stock-clock is granted.
It looks like, there is a table with CPU-types and WU-types to look up the granted credit - and this does not take oced rigs into consideration.

I am sorry for my poor english, I can not explain it any better.

Jochen


There is no table for how much credit a CPU-type should get. Let your i7 run and compare your Average Credit for that machine with a machine with the same CPU. Let your average credit to settle (1-2 weeks)... and then compare.
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Message 65824 - Posted: 25 Apr 2010, 19:41:21 UTC - in response to Message 65817.  

I had this rig running Rosetta for at least 3 months last year... I would consider this a long term. My rig is claiming the correct amount of credits, but just gets granted, what the same CPU@stock-clock is granted.
It looks like, there is a table with CPU-types and WU-types to look up the granted credit - and this does not take oced rigs into consideration.

I am sorry for my poor english, I can not explain it any better.

Jochen


Hi Jochen

Chilean is right - you're looking at the wrong numbers. A difference between claimed and granted credit is irrelevant - you should be looking at credit per hour or RAC, which will both show that your overclocked machine gets more credit than your stock-speed machine.

HTH
Danny
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Message 65827 - Posted: 25 Apr 2010, 20:55:38 UTC

Thanks for all your answers. I will wait. There were not many 920s around last year, so I could not compare the RAC. But still, looking at the granted credits for similar WUs on a stock 920 and on my oced 920... We will see in a couple of weeks.

Jochen


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Message 65828 - Posted: 25 Apr 2010, 21:19:07 UTC - in response to Message 65827.  

Thanks for all your answers. I will wait. There were not many 920s around last year, so I could not compare the RAC. But still, looking at the granted credits for similar WUs on a stock 920 and on my oced 920... We will see in a couple of weeks.

Jochen


WUs are made up of a varying numbers of decoys (models) - the number depends on how many your machine can fit into your WU time preference. Your overclocked machine might be fitting 30% more decoys into each WU, which will result in it getting 30% more granted credit on average. The claimed credit is just based on the computer's benchmark scores x WU time so is often inaccurate.

Danny


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Message 65837 - Posted: 26 Apr 2010, 11:56:15 UTC - in response to Message 65827.  

Thanks for all your answers. I will wait. There were not many 920s around last year, so I could not compare the RAC. But still, looking at the granted credits for similar WUs on a stock 920 and on my oced 920... We will see in a couple of weeks.

Jochen


You cannot compare your 920 to someone elses 920, their motherboard could be more efficient, ie more expensive, their memory could be faster, their harddrive could be faster, they could be using their video card to crunch with and you are not, you are playing games sometimes and they are not, etc ,etc, etc. Yes it would be nice if you could find another identical machine that that person does exactly the same thing you do, but in real life you cannot. I have a bunch of computers on line that only crunch, nothing else, that makes them faster than any other pc like them that their user does something, anything, with besides crunching. I also have my cache set fairly low, less than a day, that reduces the flucuations caused by returning units once every few days or even once a week or more. In short there are MANY variables that will cause even 2 identical machines to have a different RAC than each other, some of which we can control, some of which we cannot. Do you have the screen saver running? That can slow down the pc too!
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Message 65838 - Posted: 26 Apr 2010, 14:56:05 UTC

Another key reason it is not meaningful to compare RAC of one machine to that of another participant is that you have no idea how many hours per day their machine is on, nor how many projects they are running. They could easily have a 8 core machine running one climate prediction model and 7 Rosetta tasks for example. They might have powered down for the night when they installed Windows updates, etc.

It seems one concern is that your overclocking is not recognized. This is not the case. A successfully OC'd machine will claim more credit per hour, and produce more models and therefore more granted credit per hour then the same machine running the same tasks without the OC. But note that the granted credit may still be consistently below the claim, even though the credit granted per hour has indeed increased.
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Message 65839 - Posted: 26 Apr 2010, 18:06:42 UTC - in response to Message 65838.  

A successfully OC'd machine will claim more credit per hour, and produce more models and therefore more granted credit per hour then the same machine running the same tasks without the OC.


Is there a guide how to calculate this credit per hour value? I did a quick forum search, but could not find something.

Jochen

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Message 65845 - Posted: 26 Apr 2010, 23:09:31 UTC - in response to Message 65839.  

A successfully OC'd machine will claim more credit per hour, and produce more models and therefore more granted credit per hour then the same machine running the same tasks without the OC.


Is there a guide how to calculate this credit per hour value? I did a quick forum search, but could not find something.

Jochen


BOINC Manager shows you an X-Y graph for the total credit of your machine, just pick two point (1 day) and divide by 24. Best way to figure it out IMO.
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Message 65849 - Posted: 27 Apr 2010, 4:47:49 UTC - in response to Message 65839.  

RAC varies too heavily, IMO, to give one reliable value. In my opinion it is a pretty useless exercise. I look at my RAC to get an indication, knowing it is not very reliable.
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Message boards : Number crunching : Credit always low



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