[bitbake-devel] [PATCH 7/8] command.py: add new command to get the CPU info

[Wang, Shane]

Richard Purdie wrote on 2012-01-11:

> On Wed, 2012-01-11 at 11:03 +0800, Dongxiao Xu wrote:
>> Add new API in command.py to get the CPU core and threads information
>> in order to set the appropriate BB_NUMBER_THREADS and PARALLEL_MAKE
>> variables.
>> 
>> Signed-off-by: Shane Wang <shane.wang at intel.com>
>> ---
>>  bitbake/lib/bb/helper.py |   39
>>  +++++++++++++++++++++++++++++++++++++++ lib/bb/command.py        |  
>>  12 ++++++++++++ 2 files changed, 51 insertions(+), 0 deletions(-)
>>  create mode 100644 bitbake/lib/bb/helper.py
>> diff --git a/bitbake/lib/bb/helper.py b/bitbake/lib/bb/helper.py new
>> file mode 100644 index 0000000..291158b --- /dev/null +++
>> b/bitbake/lib/bb/helper.py @@ -0,0 +1,39 @@ +# +# Helper for BitBake
>> Graphical GTK User Interface +# +# Copyright (C) 2011        Intel
>> Corporation +# +# Authored by Shane Wang <shane.wang at intel.com> +# +#
>> This program is free software; you can redistribute it and/or modify +#
>> it under the terms of the GNU General Public License version 2 as +#
>> published by the Free Software Foundation. +# +# This program is
>> distributed in the hope that it will be useful, +# but WITHOUT ANY
>> WARRANTY; without even the implied warranty of +# MERCHANTABILITY or
>> FITNESS FOR A PARTICULAR PURPOSE.  See the +# GNU General Public
>> License for more details. +# +# You should have received a copy of the
>> GNU General Public License along +# with this program; if not, write to
>> the Free Software Foundation, Inc., +# 51 Franklin Street, Fifth Floor,
>> Boston, MA 02110-1301 USA. + +import os + +class CpuInfo(object): + +  
>>  coefficient = 4
> 
> This is setting off alarm bells...
> 
>> +    @classmethod
>> +    def getNumOfCpus(cls):
>> +        pfile = os.popen('cat /proc/cpuinfo | grep cpu\ cores')
>> +        num = len(pfile.readlines())
>> +        return num
> 
> You can get this number with something like:
> 
> import multiprocessing
> multiprocessing.cpu_count()
Good to see this works, will change that.

> 
>> +    @classmethod +    def getNumOfCpuCores(cls): +        pfile =
>> os.popen('cat /proc/cpuinfo | grep cpu\ cores | cut -d: -f2') +       
>> contents = pfile.readlines() +        num = int(contents[0]) +       
>> return num
> 
> I'm curious what you're using the number of cores to do? It doesn't seem
> used by your code?
> 
> 
>> diff --git a/lib/bb/command.py b/lib/bb/command.py
>> index 05555c5..eaf8236 100644
>> --- a/lib/bb/command.py
>> +++ b/lib/bb/command.py
>> @@ -30,6 +30,7 @@ Commands are queued in a CommandQueue
>> 
>>  import bb.event
>>  import bb.cooker
>> +import bb.helper
>> 
>>  class CommandCompleted(bb.event.Event):
>>      pass
>> @@ -173,6 +174,17 @@ class CommandsSync:
>>          """
>>          command.cooker.reset()
>> +    def getDefaultNumOfThreads(self, command, params): +        """ + 
>>       Get the default number of threads on the server = number of CPUs
>> +        """ +        return bb.helper.CpuInfo.getNumOfCpus() + +   
>> def getMaxNumOfThreads(self, command, params): +        """ +       
>> Get the max number of threads that the server can tolerate +        """
>> +        return bb.helper.CpuInfo.getNumOfCpus() *
>> bb.helper.CpuInfo.coefficient
>> 
> 
> I can understand needing to query the number of cpus but this last
> function seems rather arbitrary. If you want to do bounds checking, I'd
> suggest just adding the factor of 4 into the UI.
OK

> I'm still not convinced
> we should be setting any value for this though, or doing any bounds
> checking on the value.
Which value? We hope when the UI starts up, the UI can take advantage of cpus for build and set it as default.
But users can change between 0 ~ max num of threads.

> 
> 
> My only other comment would be to use bb.utils instead of creating a
> bb.helper.
> 
> Cheers,
> 
> Richard
> 
> 
> 
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