Re: ARAnyM speed
Britton Dodd dixit:
>What virtualization subsystem are you running? I have a i7 920 at home
>and it's pretty fast.
ARAnyM on bare metal Debian/i386.
>The only thing I can think of is maybe your running into a scenario
>where your VMs are pinned to threads that share the same CPU Core, and
>that might be inducing a bottle-neck somewhere.
Hm. I can try pinning one on cpu#7 only, or not pinning them at all.
(15 minutes later)
Nope, I get still about 47 BogoMIPS for both the one pinned on cpu#7
(the other running VMs are pinned to cpu#0 #1 #2 and #3) and the one
unpinned, while the system was half idle.
As an “ouch” on the side: the other VMs have ~70 BogoMIPS.
>Just out of curiosity, why pin the VM threads? The scheduler from what
>I've seen does a pretty good job with managing thread usage. Of
There are no threads. ARAnyM is a single CPU (plus chips) which is
emulated by a single user-space process, and not letting that flip
between CPUs increases system performance.
>monitoring as well. And if 2 VMs are pinned to logical CPU0 and CPU1,
>they *might* be fighting for CPU time because of Intel HyperThreading.
Does Intel still use HT? I thought it was a bad idea-thing of the past?
Does the CPU I have use it?
But on the other hand, if you see above, even if I pin it to just cpu#7
I get the bad performance. Also, if I pin it on cpu#6 (the “other half”
if I got the info right) I get the same (about 45-46 BogoMIPS).
/sys/devices/system/cpu/cpu{0-7}/cpufreq/scaling_governor = performance
In /proc/cpuinfo I also see the MHz up on the max. I’m out of ideas.
>And Turbo Boost *may* also be playing a part in this too..although
>I've rarely *if ever* seen it kick in on Linux…especially if your CPU
I have no idea what that is…
>isn't exceeding the maximum TDP (thermal design power). If a CPU core
>or two needs extra speed, the i7 will temporarily adjust the
>multiplier up a couple of points on-the-fly, as long as heat output
>doesn't exceed the maximum.
… or how to check for that.
>Other things like AHCI mode for SATA vs IDE emulation on SATA make a
>huge difference with respect to I/O too.
Erm. I use NatFeat disc access. But this is purely about vCPU
performance.
>I hope none of this offended you -- I'm just trying to help, as I
>really admire what you guys are doing with 68k equipment.
No, not a problem. One thing I’d like to do is to take this back
to the mailing list, so maybe others know. If that’s ok for you
I’ll bounce these messages too (I won’t publish private mails
without asking, normally).
Thanks,
//mirabilos
--
“Having a smoking section in a restaurant is like having
a peeing section in a swimming pool.”
-- Edward Burr
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