[OpenIndiana-discuss] zsf send/receive performance

[wim at vandenberge.us]

That is an interesting thought. I did check the aggregate CPU utilization (Dual
6-core 2.0GHz Xeon, E5-2630L) and overall it looks fine with a load average
below 0.5 during transfers. However,  I have not checked if there is a single
thread that is blocking the process. I guess the cheap way to verify your
assumption is to run the process on a faster processor. If the throughput goes
up with the speed of the CPU that would indicate we're on the right track. I
think we have a couple of E-2637v2's laying around, let me see if I can get
those swapped in.



W



 > On December 9, 2013 at 3:15 PM Jim Klimov <jimklimov at cos.ru> wrote:
>
>
> Reading your description, I thought "can it be a single-CPU
> performance issue?" Perhaps, decompressing your datasets
> (or compressing upon write - though the /dev/null experiment
> rules that out), or building the stream, or any other step
> in your data path, might for some reason be a single-threaded
> task. Running several in parallel splits them across many
> cores, but one is slow.
>
> Not being a ZFS developer, I am not ready to check and point
> the place in code where that guess might be (dis-)proved,
> but at least I'd start digging (and asking) with such an
> assumption :)
>
> At least, there are many things in parallel IT processing
> that are made fast by sheer scale of concurrent independent
> tasks, rather than (expensively) trying to parallelize the
> code inside. And on average the cheap approach pays off ;)
>
> //Jim
>
>
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