requesting input on specs for a new Poky build server

requesting input on specs for a new Poky build server

[Joe Sauer]

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I have the pleasure of spec'ing out a new server for doing Poky builds (we
are at Green 3.3.1).  As a reference point, my desktop machine is a
quad-Xeon @ 2.5 GHz with 4GB of RAM and SATA disk.  I can do a full "clean"
build for our LabQuest (armv5te) in 2 hours.

Here are some questions I would like to get feedback on regarding a build
server:

1.  Would I get better build time going with more procs (8?) or faster procs
(3+ GHz)?

2.  Are SATA drives OK, or should I go with RAID to get better R/W
performance?

3.  If I have to choose one or the other, should I go with faster procs or
faster disk I/O?

Thanks!

--Joe Sauer
Vernier Software & Technology

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Re: requesting input on specs for a new Poky build server

[Tom Rini]

On 04/11/2011 02:50 PM, Joe Sauer wrote:
> I have the pleasure of spec'ing out a new server for doing Poky builds
> (we are at Green 3.3.1).  As a reference point, my desktop machine is a
> quad-Xeon @ 2.5 GHz with 4GB of RAM and SATA disk.  I can do a full
> "clean" build for our LabQuest (armv5te) in 2 hours.
> 
> Here are some questions I would like to get feedback on regarding a
> build server:
> 
> 1.  Would I get better build time going with more procs (8?) or faster
> procs (3+ GHz)?
> 
> 2.  Are SATA drives OK, or should I go with RAID to get better R/W
> performance?
> 
> 3.  If I have to choose one or the other, should I go with faster procs
> or faster disk I/O?

If you're on somewhat of a budget, the general rule of thumb about going
for last months fastest processor (as opposed to the one just released)
is probably a wise bet.  And you probably want 8-12GB ram if you can fit it.

The only real and not always obvious trick is if you can afford an SSD
(and afford to kill it and replace it every so often) doing your builds
there is a real big win.

-- 
Tom Rini
Mentor Graphics Corporation

Re: requesting input on specs for a new Poky build server

[Darren Hart]

On 04/11/2011 05:03 PM, Tom Rini wrote:
> On 04/11/2011 02:50 PM, Joe Sauer wrote:
>> I have the pleasure of spec'ing out a new server for doing Poky builds
>> (we are at Green 3.3.1).  As a reference point, my desktop machine is a
>> quad-Xeon @ 2.5 GHz with 4GB of RAM and SATA disk.  I can do a full
>> "clean" build for our LabQuest (armv5te) in 2 hours.
>>
>> Here are some questions I would like to get feedback on regarding a
>> build server:
>>
>> 1.  Would I get better build time going with more procs (8?) or faster
>> procs (3+ GHz)?

I would go with more CPUs before I went with faster CPUs (at least from
2.5 to 3.3). Poky builds scale nicely to at least 16 physical cores (ie
4 quad-cores, hyperthreading is effective as well, but not so much as
physical cores), so until you get to that point, more is better in my
opinion.

>>
>> 2.  Are SATA drives OK, or should I go with RAID to get better R/W
>> performance?

A RAID 0 array of SATA drives is your best performing option (short of a
RAID 0 SSD array). You have to trade this extra performance for lower
reliability. RAID 0 has no redundancy, if one drive fails, all your data
is gone - so only keep recreatable data on the RAID array. I'd start
without RAID and test, see if you are maximizing your IO bandwidth.

>>
>> 3.  If I have to choose one or the other, should I go with faster procs
>> or faster disk I/O?

Provided you have a reasonably decent SATA controller on board, I'd opt
for _more_ procs.

> 
> If you're on somewhat of a budget, the general rule of thumb about going
> for last months fastest processor (as opposed to the one just released)
> is probably a wise bet.  And you probably want 8-12GB ram if you can fit it.
> 
> The only real and not always obvious trick is if you can afford an SSD
> (and afford to kill it and replace it every so often) doing your builds
> there is a real big win.

The failures are the scary part as you mentioned. I keep my git
repositories and downloads on an SSD and do my builds on a 2 disk RAID
array. I usually see either build dependencies or CPU as the bottleneck
before IO.

-- 
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel

Re: requesting input on specs for a new Poky build server

[Richard Purdie]

Hi Joe,

On Mon, 2011-04-11 at 14:50 -0700, Joe Sauer wrote:
> I have the pleasure of spec'ing out a new server for doing Poky builds
> (we are at Green 3.3.1).  As a reference point, my desktop machine is
> a quad-Xeon @ 2.5 GHz with 4GB of RAM and SATA disk.  I can do a full
> "clean" build for our LabQuest (armv5te) in 2 hours.
> 
> Here are some questions I would like to get feedback on regarding a
> build server:
> 
> 1.  Would I get better build time going with more procs (8?) or faster
> procs (3+ GHz)?
> 
> 2.  Are SATA drives OK, or should I go with RAID to get better R/W
> performance?
> 
> 3.  If I have to choose one or the other, should I go with faster
> procs or faster disk I/O?

Good questions and I'm not sure I have a definitive answer for you. Some
parts of the build are I/O bound, some are CPU bound and I think you
could see benefits by improving both at this point in time. I'd suspect
CPU still wins as the bigger bottleneck though. Disk I/O can partly be
worked around by a little more RAM.

Cheers,

Richard