[oe] PARALLEL_MAKE

[Ulf Samuelsson]

> On Thu, Mar 12, 2009 at 11:49:30PM -0400, Denys Dmytriyenko wrote:
>> On Thu, Mar 12, 2009 at 06:38:54PM -0700, Khem Raj wrote:
>> > On Thursday 12 March 2009 16:32:16 Ulf Samuelsson wrote:
>> > > Is there any activity to make this more useful?
>> > > Just managed to install a Core i7 machine, which speeded
>> > > up my Buildroot build from about 4 hours to less than 1 hour.
>> > > (There was an error in the build right at the end,
>> > > so it could have been downto 40 minutes or so)
>> > > Building the cross compiler took 10 minutes with "make -j 16"
>> > > compared to 1-2 hours on a P4 @ 3GHz.
>> > >
>> > > Openembedded does not seem to use PARALLEL_MAKE extensively.
>> > > I have the frequency meter activated for all 8 CPUs in the Core i7,
>> > > and most of the time the CPUs seems to idle at 1.6 GHz,
>> > > with one CPU (or rarely 2) are running at the full 2.67 GHz.
>> > >
>> > > Last time I built OE on a P4@ 3 GHz it took ~40 hours
>> > > for the SAM9263, so some speedup would be nice.
>> > > Maybe we should make an effort?
>> >
>> > I use
>> >
>> > PARALLEL_MAKE = "-j4"
>> > BB_NUMBER_THREADS = "2"
>> >
>> > in my local.conf. I see my core 2 duo machine spawning parallel tasks.
>>
>> I'm setting 4/4 to the above two variables on my Quad Core and it loads 
>> all 4
>> cores at 100% almost all the time. Sometimes it slows down due to the
>> bottleneck in the harddrive access...
>
> On the dual dual-core (4 total) boxes I have, I do -j6/4 threads.  On my
> new quad-core box I haven't yet had a chance to figure out what's best.
> I also use -j6/4 threads on an older dual-core amd64 box we've got
> around and that seems best for my tasks at least (I tried a few
> combinations of more jobs/threads and less and both were slower).
>

I looked at a few recipies which by a stanrge coincidence had 
PARALLEL_MAKE="",

When, I rechecked, I had
PARALLEL_MAKE ="-j 16"
as well and this should be
PARALLEL_MAKE ="-j16"

Changed to
PARALLEL_MAKE ="-j8"
BB_NUMBER_THREADS = "2"

I see some more cores beeing used.
The initial setup after you changed local.conf seems to run on a single core 
though.

Thanks for the help.
Ulf Samuelsson


> -- 
> Tom Rini
>
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