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0 pointspertymcpert6y ago0 comments

What do you think is a good performance improvement then?

0 comments

(and to the two other responses)

If your workload is already well parallelized, then, yes 20% is quite significant. However, working to parallelize properly over 8 rather than 4 has its own costs.

The thing that bothers me most is that 800% CPU and 500% CPU on this processor are roughly equivalent at 5x100%CPU, it makes everything very hard to reason about when planning capacity.

pertymcpertOP6y ago

I think you’re misunderstanding what HT is. It’s not true parallelism, it’s just hiding latency by providing some extra superscalar parallelism. You can’t expect it to give you actual linear improvements in performance because it’s just an illusion.

beagle36y ago

I understand that very well. But non of the standard tools that manage CPU understand that, and most people don't either.

If I had a nickel for every time I had to explain why "You are at 50% CPU now, but you can't actually run twice as many processes on this machine and get the same runtime", I'd be able to buy a large frapuccino or two at starbucks.

Perhaps I'm uninformed though - is there a tool like htop, which would give me an idea of how close am I to maxing out a CPU?

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0 comments

beagle36y ago

(and to the two other responses)

If your workload is already well parallelized, then, yes 20% is quite significant. However, working to parallelize properly over 8 rather than 4 has its own costs.

The thing that bothers me most is that 800% CPU and 500% CPU on this processor are roughly equivalent at 5x100%CPU, it makes everything very hard to reason about when planning capacity.

pertymcpertOP6y ago

beagle36y ago

I understand that very well. But non of the standard tools that manage CPU understand that, and most people don't either.

Perhaps I'm uninformed though - is there a tool like htop, which would give me an idea of how close am I to maxing out a CPU?

1 more reply

j / k navigate · click thread line to collapse