Intel i7 CPU

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Message 57243 - Posted: 26 Nov 2008, 12:04:29 UTC

If you got one, post the PC here to see the benchmarks.
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Message 57246 - Posted: 26 Nov 2008, 13:13:11 UTC

according to boincstats there are only 2 i7 cpus running Rosetta so far (that i could find):

Intel(R) Core(tm) i7 CPU 940 @ 2.93GHz

http://boincstats.com/stats/host_cpu_stats.php?pr=rosetta&teamid=&st=1400&or=

I'm not sure how to find one of those in the rosetta stats though...

Incidentally, I also spotted a transmeta CPU in the list!
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Message 57269 - Posted: 27 Nov 2008, 6:03:06 UTC - in response to Message 57246.  
Last modified: 27 Nov 2008, 6:04:52 UTC

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Message 57281 - Posted: 27 Nov 2008, 13:35:48 UTC

hmmm.... from a v small sample size it looks like nehalem is currently slower than kentsfield! I assume because of its smaller L2 cache?

from one page of results from that machine, it gets on average 20.5 credits per core per hour. My Q6600 gets 18.2 per core-hour, but the i7 is 3.2GHz against my 2.4GHz, so i7 would get 20.5/3.2*2.4 = 15.4 credits per hour at 2.4GHz...

If i use my Q6600's RAC (1570) that falls to 1570/24/4 = 16.1 credits per core-hour, but that's still a bit higher than the i7.

Looks like Penryn will still be top-dog here, although it might vary with different tasks, or if the bakerlab guys can implement some kind of optimisations for SSE etc.
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Message 57283 - Posted: 27 Nov 2008, 14:20:55 UTC - in response to Message 57281.  

hmmm.... from a v small sample size it looks like nehalem is currently slower than kentsfield! I assume because of its smaller L2 cache?

from one page of results from that machine, it gets on average 20.5 credits per core per hour. My Q6600 gets 18.2 per core-hour, but the i7 is 3.2GHz against my 2.4GHz, so i7 would get 20.5/3.2*2.4 = 15.4 credits per hour at 2.4GHz...

If i use my Q6600's RAC (1570) that falls to 1570/24/4 = 16.1 credits per core-hour, but that's still a bit higher than the i7.

Looks like Penryn will still be top-dog here, although it might vary with different tasks, or if the bakerlab guys can implement some kind of optimisations for SSE etc.


I thought the Nehalems would still have butt-loads of L2 Cache even though they fixed the ridiculous CPU-Northbridge-CPU "interCore" communication. Which reduces the delay of communication between cores.

Oh well. We'll have too see a larger sample.
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Message 57285 - Posted: 27 Nov 2008, 16:03:52 UTC - in response to Message 57283.  

hmmm.... from a v small sample size it looks like nehalem is currently slower than kentsfield! I assume because of its smaller L2 cache?

from one page of results from that machine, it gets on average 20.5 credits per core per hour. My Q6600 gets 18.2 per core-hour, but the i7 is 3.2GHz against my 2.4GHz, so i7 would get 20.5/3.2*2.4 = 15.4 credits per hour at 2.4GHz...

If i use my Q6600's RAC (1570) that falls to 1570/24/4 = 16.1 credits per core-hour, but that's still a bit higher than the i7.

Looks like Penryn will still be top-dog here, although it might vary with different tasks, or if the bakerlab guys can implement some kind of optimisations for SSE etc.


I thought the Nehalems would still have butt-loads of L2 Cache even though they fixed the ridiculous CPU-Northbridge-CPU "interCore" communication. Which reduces the delay of communication between cores.

Oh well. We'll have too see a larger sample.
256KB per core L2 - the L3 is much higher latency (although obviously a lot better than going to RAM). Same setup as Barca/Deneb I believe...

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Message 57288 - Posted: 27 Nov 2008, 20:44:52 UTC - in response to Message 57281.  

hmmm.... from a v small sample size it looks like nehalem is currently slower than kentsfield! I assume because of its smaller L2 cache?

from one page of results from that machine, it gets on average 20.5 credits per core per hour. My Q6600 gets 18.2 per core-hour, but the i7 is 3.2GHz against my 2.4GHz, so i7 would get 20.5/3.2*2.4 = 15.4 credits per hour at 2.4GHz...

If i use my Q6600's RAC (1570) that falls to 1570/24/4 = 16.1 credits per core-hour, but that's still a bit higher than the i7.

Looks like Penryn will still be top-dog here, although it might vary with different tasks, or if the bakerlab guys can implement some kind of optimisations for SSE etc.


And if hyperthreading is turned on that will hurt the performance also a bit, though it does double the number of tasks running at the same time.
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Message 57306 - Posted: 28 Nov 2008, 9:57:09 UTC - in response to Message 57288.  
Last modified: 28 Nov 2008, 9:57:53 UTC

hmmm.... from a v small sample size it looks like nehalem is currently slower than kentsfield! I assume because of its smaller L2 cache?

from one page of results from that machine, it gets on average 20.5 credits per core per hour. My Q6600 gets 18.2 per core-hour, but the i7 is 3.2GHz against my 2.4GHz, so i7 would get 20.5/3.2*2.4 = 15.4 credits per hour at 2.4GHz...

If i use my Q6600's RAC (1570) that falls to 1570/24/4 = 16.1 credits per core-hour, but that's still a bit higher than the i7.

Looks like Penryn will still be top-dog here, although it might vary with different tasks, or if the bakerlab guys can implement some kind of optimisations for SSE etc.


And if hyperthreading is turned on that will hurt the performance also a bit, though it does double the number of tasks running at the same time.

I thought BOINC only ran one task per physical CPU now? If not, we should be telling people to do that for better throughput...
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Message 57314 - Posted: 28 Nov 2008, 14:19:23 UTC - in response to Message 57306.  

hmmm.... from a v small sample size it looks like nehalem is currently slower than kentsfield! I assume because of its smaller L2 cache?

from one page of results from that machine, it gets on average 20.5 credits per core per hour. My Q6600 gets 18.2 per core-hour, but the i7 is 3.2GHz against my 2.4GHz, so i7 would get 20.5/3.2*2.4 = 15.4 credits per hour at 2.4GHz...

If i use my Q6600's RAC (1570) that falls to 1570/24/4 = 16.1 credits per core-hour, but that's still a bit higher than the i7.

Looks like Penryn will still be top-dog here, although it might vary with different tasks, or if the bakerlab guys can implement some kind of optimisations for SSE etc.


And if hyperthreading is turned on that will hurt the performance also a bit, though it does double the number of tasks running at the same time.

I thought BOINC only ran one task per physical CPU now? If not, we should be telling people to do that for better throughput...


I don't think the OS is capable of distinguishing between a virtual and physical core. When HT is enabled, it tells the OS that it has twice the available cores (2 virtual cores per 1 physical core).

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Message 57336 - Posted: 28 Nov 2008, 21:24:18 UTC - in response to Message 57281.  

It takes a while for RAC to stabilize. Could that be the reason why I7 seems slower?

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Message 57357 - Posted: 29 Nov 2008, 17:35:52 UTC - in response to Message 57336.  

It takes a while for RAC to stabilize. Could that be the reason why I7 seems slower?


Probably.

Because the i7 beat the Intel Core 2 right out of the water in every benchmark (single or mutli threaded)
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Message 57359 - Posted: 29 Nov 2008, 19:07:57 UTC - in response to Message 57336.  
Last modified: 29 Nov 2008, 19:08:32 UTC

It takes a while for RAC to stabilize. Could that be the reason why I7 seems slower?

no - i wasn't looking at RAC, i just dumped a page of its submitted results into excel and worked out the average granted credit per hour. There's variation in the credit depending on a few factors but it gives a ball-park figure. A stable RAC is the best test though.

Maybe Nehalem will perform better if all the cores are running tasks that depend on the same files so the L3 is used more efficiently...

I've worked out why the credit from my E2180 was low - it was throttling down to 1.2GHz - it's now at 2.6GHz and i've dropped the voltage to 1.1V :) Strangely, CPU-z identifies it as an E4400...
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Message 57360 - Posted: 29 Nov 2008, 19:35:34 UTC

i'm gonna hafta have rosie wait awhile, i broke down and purchased ($210!) an i7 920. now, i have to save some $$$ for the mobo and ddr3 ram, and build the darn thing. think it'll eventually be worth the effort.

curious to see what 8 virtual cores can do 24/7 for rosie...
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Message 57361 - Posted: 29 Nov 2008, 19:57:48 UTC - in response to Message 57360.  

i'm gonna hafta have rosie wait awhile, i broke down and purchased ($210!) an i7 920. now, i have to save some $$$ for the mobo and ddr3 ram, and build the darn thing. think it'll eventually be worth the effort.

curious to see what 8 virtual cores can do 24/7 for rosie...


what do u do for a living now?

or did u just win the lotto?
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Message 57366 - Posted: 30 Nov 2008, 1:09:41 UTC
Last modified: 30 Nov 2008, 1:14:31 UTC

would love to win the lotto!!! am just a lowly law school graduate, trying to eek out a living...

$210 for the i7 was a super-sale price, regular price is $300 + $25 tax.
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Message 57371 - Posted: 30 Nov 2008, 5:09:46 UTC - in response to Message 57366.  

would love to win the lotto!!! am just a lowly law school graduate, trying to eek out a living...

$210 for the i7 was a super-sale price, regular price is $300 + $25 tax.


it would be cool to see how fast it could open up photoshop.
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Message 57380 - Posted: 30 Nov 2008, 13:59:55 UTC - in response to Message 57360.  

i'm gonna hafta have rosie wait awhile, i broke down and purchased ($210!) an i7 920. now, i have to save some $$$ for the mobo and ddr3 ram, and build the darn thing. think it'll eventually be worth the effort.

curious to see what 8 virtual cores can do 24/7 for rosie...

i'd be interested to see how good the i7 is on power consumption with Rosie running... should be very good.
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Message 57537 - Posted: 3 Dec 2008, 8:50:44 UTC
Last modified: 3 Dec 2008, 8:57:19 UTC

From these numbers it seems that Nehalem is not performing well with Rosetta. But we must consider that it has 8 logic cores, in fact the computer page on Boinc says "Number of CPUs: 8"

long-term RAC can only tell us more...
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Message 57539 - Posted: 3 Dec 2008, 9:37:05 UTC - in response to Message 57537.  

From these numbers it seems that Nehalem is not performing well with Rosetta. But we must consider that it has 8 logic cores, in fact the computer page on Boinc says "Number of CPUs: 8"

long-term RAC can only tell us more...

Previously hyperthreading hasn't helped - I'd think it would be the same for nehalem as the L2 cache will have to swap info for the two threads.
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Message 57545 - Posted: 3 Dec 2008, 14:15:51 UTC

The i7 processor has an inclusive L3 cache. Which for those who don't know what that means is basically a small portion (1MB) of the 8MB L3 cache is reserved for the contents of all 4 256KB L2 caches so that if core 1 wants something from core 3 then rather than diving straight into core 3's L2 cache it can simply go to the L3 which prevents a core from "stalling".
Hyper-threading will not improve the credits per hour of individual cores, but certainly will for the CPU as a whole. Just think of it as 2/3 + 2/3 = 4/3. So even if each "hyperthreaded" core is only 2/3 as powerful as a full core. These two add up to equal greater than the sum of its parts.
It is also true that the small amount of L2 in i7 is a concern for those applications which "cache thrash" such as Rosetta. But this effect will be minimised by the large L3 cache and the new Quickpath interconnect which much reduces latency to the main memory. So the 8 cores will be waiting less for data. The large L2 caches we have been seeing on some of the latest Core 2 CPU's are to make up for the extreme latency problems of the ancient & inadequate front side bus.
The TDP of all released Core i7 CPU's is 130W, fortunately this isn't what Rosetta will use as this figure is assuming the CPU is fed perfectly with data to process and that all instruction units (MMX SSE SSE2 etc) are being used. So I would expect the CPU itself to be knocking out more like ~90W
We also have to remember that unfortunately Intel doesn't design processors for people like us who see them as tools for science, but rather for large corporations who don't like to wait for access to massive data-bases of who's been taking too many days off etc. To this end we may have to wait for a while for Rosetta to benefit significantly from any major changes in CPU architecture. Also the advent of green computing could see less major improvements too :(
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Message boards : Number crunching : Intel i7 CPU



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