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"[...] ARM servers are a big part of the future [...]" Has anyone actually compared x86 and ARM doing some sort of comparable task, and measured how much power

by runeks 14y ago

"[...] ARM servers are a big part of the future [...]" Has anyone actually compared x86 and ARM doing some sort of comparable task, and measured how much power they both consume performing the same task? I know ARM uses a lot less power than x86, but if it uses 10 times as little power but takes 20 times as long to do the same task as an x86 server chip, it still uses more power. I'm not saying it isn't more power efficient than x86 (it certainly has that potential, because of all the old cruft in x86), but I just haven't seen any evidence that supports this claim. Or am I missing the point? Is power efficiency not the main reason for ARM servers?

timthorn 14y ago
It all depends on the workload, but one public comparison (from the vendor and in a press release, but with some figures): http://www.low-latency.com/blog/cantor-evaluating-calxeda-arm-chips-10x-breakthrough http://www.low-latency.com/blog/cantor-evaluating-calxeda-ar...
AUmrysh 14y ago
The Ubuntu team was talking at SELF a few years back about using ARM clusters as web servers because of the low cost, high efficiency, and high core density you can achieve with the low-heat ARM chips.
mbell 14y ago
In many server applications your not CPU bound but rather IO bound. In those applications using the lowest power CPU makes sense. These are the applications ARM seems to be targeting first. Examples: $5 month static + php only website hosting market, front end load balancing, static file serving, etc. The other possible target is embarrassingly parallel work loads where you really just want to cram as many cores into a given space as possible. Usually the limit of how many cores you can put in a rack is either power or cooling, not space. Where you probably won't see ARM in the near term is on work loads that are highly single threaded and performance critical. I think this is exactly the type of situation your describing.
sciurus 14y ago
See Google's paper 'Brawny cores still beat wimpy cores, most of the time'. It concludes that 'Slower but energy efficient “wimpy” cores only win for general workloads if their single-core speed is reasonably close to that of mid-range “brawny” cores.' http://research.google.com/pubs/archive/36448.pdf http://research.google.com/pubs/archive/36448.pdf HTML version at http://bit.ly/KOhENi http://bit.ly/KOhENi
ajross 14y ago
ARM boards are generally more power efficient for any given compute unit you want to benchmark, but it's not a huge advantage And note that there are Intel solutions in the "cheap, low power" market too. There are ~$80 Cedar Trail boards (I forget the part numbers off-hand) which take 2GB of DDR3 memory and run on 15W or so at full CPU utilization.

by runeks 14y ago

timthorn 14y ago

It all depends on the workload, but one public comparison (from the vendor and in a press release, but with some figures): http://www.low-latency.com/blog/cantor-evaluating-calxeda-arm-chips-10x-breakthrough http://www.low-latency.com/blog/cantor-evaluating-calxeda-ar...

AUmrysh 14y ago

The Ubuntu team was talking at SELF a few years back about using ARM clusters as web servers because of the low cost, high efficiency, and high core density you can achieve with the low-heat ARM chips.

mbell 14y ago

In many server applications your not CPU bound but rather IO bound. In those applications using the lowest power CPU makes sense. These are the applications ARM seems to be targeting first. Examples: $5 month static + php only website hosting market, front end load balancing, static file serving, etc. The other possible target is embarrassingly parallel work loads where you really just want to cram as many cores into a given space as possible. Usually the limit of how many cores you can put in a rack is either power or cooling, not space. Where you probably won't see ARM in the near term is on work loads that are highly single threaded and performance critical. I think this is exactly the type of situation your describing.

sciurus 14y ago

See Google's paper 'Brawny cores still beat wimpy cores, most of the time'. It concludes that 'Slower but energy efficient “wimpy” cores only win for general workloads if their single-core speed is reasonably close to that of mid-range “brawny” cores.' http://research.google.com/pubs/archive/36448.pdf http://research.google.com/pubs/archive/36448.pdf HTML version at http://bit.ly/KOhENi http://bit.ly/KOhENi

ajross 14y ago

ARM boards are generally more power efficient for any given compute unit you want to benchmark, but it's not a huge advantage And note that there are Intel solutions in the "cheap, low power" market too. There are ~$80 Cedar Trail boards (I forget the part numbers off-hand) which take 2GB of DDR3 memory and run on 15W or so at full CPU utilization.