[poky] [RFC PATCH 1/1] local.conf.sample: update suggestions for BB_NUMBER_THREADS and PARALLEL_MAKE

[Darren Hart]

On 06/17/2011 08:21 PM, Darren Hart wrote:
> 
> 
> On 06/17/2011 08:16 PM, Joshua Lock wrote:
>> It's been suggested that BB_NUMBER_THREADS should be 2 * the number of cores
>> and PARALLEL_MAKE should be equal to the number of cores available on the
>> build machine.
>>
>> Update local.conf.sample to suggest this.
>>
>> Signed-off-by: Joshua Lock <josh at linux.intel.com>
>> ---
>>  meta-yocto/conf/local.conf.sample |    4 +++-
>>  1 files changed, 3 insertions(+), 1 deletions(-)
>>
>> diff --git a/meta-yocto/conf/local.conf.sample b/meta-yocto/conf/local.conf.sample
>> index ea32b81..43d06e6 100644
>> --- a/meta-yocto/conf/local.conf.sample
>> +++ b/meta-yocto/conf/local.conf.sample
>> @@ -9,7 +9,9 @@ CONF_VERSION = "1"
>>  #SSTATE_DIR ?= "${TOPDIR}/sstate-cache"
>>  
>>  # Uncomment and set to allow bitbake to execute multiple tasks at once.
>> -# For a quadcore, BB_NUMBER_THREADS = "4", PARALLEL_MAKE = "-j 4" would
>> +# Recommended values are twice the number of processor cores for
>> +# BB_NUMBER_THREADS and the number of processor cores for PARALLEL_MAKE
>> +# For a quadcore, BB_NUMBER_THREADS = "8", PARALLEL_MAKE = "-j 4" would
> 
> Hrm, where is this coming from? In my experience it works better the
> other way around. We probably also need to be explicit about cores
> versus threads.

OK, let's get some real number behind this.

I'm running the attached script on a quadcore (8 thread) i7 system with
8 GB of RAM. an SSD for the OS, and a single spinning disk for the build.

We'll see how things look in... 13 2 ^ 2 * 24 / ... 14.08 days ...
assuming I don't burn something up first.... maybe I should have
programmed in a sleep? nah, that's what the "rm -rf tmp" is for ;-)

Would be nice to have some runtime atsar disk, sched, fault stats as well...

>>  # be appropriate.
>>  # BB_NUMBER_THREADS = "4"
>>  # Also, make can be passed flags so it run parallel threads e.g.:
> 

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