Jul 28, 2013, 12:42 PM
Post #4 of 6
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On Thu, Jul 25, 2013 at 8:00 AM, Bob Sanders <rsanders@sgi.com> wrote:
> Mark Knecht, mused, then expounded:
>> Hi all,
>> I'm wondering what folks who understand Linux configuration better
>> than I do about a problem like this. I run media all day while working
>> on my Gentoo/KDE box. The machine is generally over powered for 99% of
>> the work I do. It works _very_ hard when I kick off big numeric runs
>> (i.e. 100% usage for 2-30 minutes) but most of the time CPU usage is
>> running at <1-2% while I'm doing things like editing code and watching
>> a movie at the same time/
>>
>> What I do notice however is that whether I'm watching NetFlix in a
>> VM or a movie on disk using VLC, when I insert a DVD I almost always
>> get a glitch of 1-2 seconds while the system figures out what to do
>> with the DVD. I see some CPU usage, but it's not like 12 processors go
>> to 100%.
>>
>
> As no one has stepped in here...Pretty much everything I;m suggesting,
> you are going to hate.
>
> - Turn off that system sucking automount daemon.
>
> Hopefully, that fixes the issue for you. The rest are more drastic.
>
> Here are the important things for a VM host, in order of decreasing
> importance -
>
> 1) Storage - needs twice as much, must be fast. 7200 RPM SATA drives
> are acceptable for read only NFS stores.
>
> 2) Memory - all DIMM slots filled, 8GB 1600 PC3-DDR DIMMS minimum.
> Faster, lower latency, DIMMs preferred, but motherboard/bios may
> down clock them.
>
> 3) Network - Wide bandwidth (Probably not an issue for you). 10GigE
> minimum. Or bond at least 4 GigE ports to act as a single pipe.
>
> 4) CPU - Lower core count, 8-cores/socket max. More eats up I/O
> Bandwidth, adds latency, generates wait states. Better to
> oversubscribe the cpu than anything else.
>
> On an even more micro level -
>
> Storage - Make sure you have seperate drives for the OS - mostly read
> only), /var - mostly write, and /home - mostly read, light write.
> Typical setup would be a single SSD for the OS, RAID 1 for /var and
> whatever RAID you like for /home using 10K RPM SAS drives preferred.
>
> Use the proper file system - large sequential files: media, VM
> images, etc. need XFS. Small r/w files need - EXT3.
>
> Use a proper hardware RAID card - not a software raid. Proper
> hardware raid cards will require a x8 PCIe slot and cost a few
> hundred dollars.
>
> Reduce the cpu core count to 4 and offload your numeric compute
> requirements to a stack of RasberryPI compute engines, using your
> main system as a head node for the cluster.
>
> Bob
Bob,
Thanks for the ideas. Sort of reminds me of the old joke:
Patient: "Doctor, it hurts when I do this."
Doctor: "So don't do that."
At some point, being that >95% of the time I'm watching either NetFlix
or Hulu streaming services, or a movie that I've ripped, I could
simply purchase a TV and Roku (or a TV with built-in streaming), mount
it on the wall above my 3 monitors and simply not use the computer to
do any of this stuff. It might be less expensive!
Since writing the original post I've sort of decided the problem is
so complex I'll likely never find the best answer. It turns out I was
doing all my streaming in a Win XP VM in VMWare Player. No good reason
other than it was an older and stable VM that was on the machine so I
was using it. I switched to streaming in a Win 7 Virtualbox VM and am
not seeing and problems at all. I can insert DVDs and rip using
Handbrake while streaming from Hulu and don't see any glitches. I
don't know if it's Virtualbox being better or Win 7 being better but
it works so that's good enough for me.
This doesn't solve the movie in VLC part of it but that's not a big
deal as I don't do that very often.
It does seem to me that logically the knob I should be turning is a
deeper network buffer in VMWare but I haven't looked or found anything
that drives that directly and likely will not look if things continue
to work well.
I will keep your inputs in mind going forward. This Core i7 980
Extreme machine was built in 2010 so it's getting a little long in the
tooth. Turns out that other than going with a high end RAID controller
there isn't a really good way to take advantage of 6Gb/S SATA drives
without going to a new motherboard so I've been pondering when I might
do that.
In terms of _really_ offloading compute cycles the strategy I''m
trying to prepare for with my own code, most of it written in R, is to
offload it to some dedicated NVidia GPUs. For a non-professional
programmer such as myself that's quite a stretch though.
Thanks for the inputs.
Cheers,
Mark