Infrastructure Software

Hi everyone,

I couldn't find anyone here asking about it, so I'll throw this out there. I've noticed in my testing that ZFS throughput falls off pretty sharply with Solaris 11.1, largely due to processor usage. For some reason, it appears that Solaris 11.1 refuses to let ZFS use more than 50% of the processor (verified in mpstat and top, on 2 different bare-metal boxes and a VMware installation). Metal installations were on a Dell Poweredge 2950 (yeah I know, old), a Supermicro (Xeon E3-1240), and the VMware installation was using 6 vCPUs under ESXi 5.1 on a Supermicro server as well (Xeon E5-2670). All exhibit the same strange behavior on Solaris 11.1 - none of them have this problem on Solaris 11.0.

The long and the short of it is that if you look at mpstat, you'll see either half the cores in the box pegged or you'll see all the cores hovering around 50%. Being able to adjust Hyperthreading readily on the E3 box bore this out pretty well, the difference between 650MB/s and 320MB/s (with hyperthreading on, I see 4 cores pegged, with it disabled, I see the four physical cores hovering at 50%).

Is this a bug or a "feature"?

If the former, does anyone know if it's fixed in an SRU? I have a potential storage project going on with sales that is being jeopardized by this, and I either need to know that it's a bug that's been fixed already or is being fixed.

If it's the latter, is it tunable? If so, how?

Answers would be greatly appreciated, and if you've run into this as well that would be good to know.

-J