Re: [PATCH] validate_abi: build faster by augmenting make with job count

["Wiles, Keith" <keith.wiles@intel.com>]

> On Jul 21, 2016, at 10:06 AM, Neil Horman <nhorman@redhat.com> wrote:
> 
> On Thu, Jul 21, 2016 at 02:09:19PM +0000, Wiles, Keith wrote:
>> 
>>> On Jul 21, 2016, at 8:54 AM, Neil Horman <nhorman@tuxdriver.com> wrote:
>>> 
>>> On Wed, Jul 20, 2016 at 10:32:28PM +0000, Wiles, Keith wrote:
>>>> 
>>>>> On Jul 20, 2016, at 3:16 PM, Neil Horman <nhorman@tuxdriver.com> wrote:
>>>>> 
>>>>> On Wed, Jul 20, 2016 at 07:47:32PM +0000, Wiles, Keith wrote:
>>>>>> 
>>>>>>> On Jul 20, 2016, at 12:48 PM, Neil Horman <nhorman@redhat.com> wrote:
>>>>>>> 
>>>>>>> On Wed, Jul 20, 2016 at 07:40:49PM +0200, Thomas Monjalon wrote:
>>>>>>>> 2016-07-20 13:09, Neil Horman:
>>>>>>>>> From: Neil Horman <nhorman@redhat.com>
>>>>>>>>> 
>>>>>>>>> John Mcnamara and I were discussing enhacing the validate_abi script to build
>>>>>>>>> the dpdk tree faster with multiple jobs.  Theres no reason not to do it, so this
>>>>>>>>> implements that requirement.  It uses a MAKE_JOBS variable that can be set by
>>>>>>>>> the user to limit the job count.  By default the job count is set to the number
>>>>>>>>> of online cpus.
>>>>>>>> 
>>>>>>>> Please could you use the variable name DPDK_MAKE_JOBS?
>>>>>>>> This name is already used in scripts/test-build.sh.
>>>>>>>> 
>>>>>>> Sure
>>>>>>> 
>>>>>>>>> +if [ -z "$MAKE_JOBS" ]
>>>>>>>>> +then
>>>>>>>>> +	# This counts the number of cpus on the system
>>>>>>>>> +	MAKE_JOBS=`lscpu -p=cpu | grep -v "#" | wc -l`
>>>>>>>>> +fi
>>>>>>>> 
>>>>>>>> Is lscpu common enough?
>>>>>>>> 
>>>>>>> I'm not sure how to answer that.  lscpu is part of the util-linux package, which
>>>>>>> is part of any base install.  Theres a variant for BSD, but I'm not sure how
>>>>>>> common it is there.
>>>>>>> Neil
>>>>>>> 
>>>>>>>> Another acceptable default would be just "-j" without any number.
>>>>>>>> It would make the number of jobs unlimited.
>>>>>> 
>>>>>> I think the best is just use -j as it tries to use the correct number of jobs based on the number of cores, right?
>>>>>> 
>>>>> -j with no argument (or -j 0), is sort of, maybe what you want.  With either of
>>>>> those options, make will just issue jobs as fast as it processes dependencies.
>>>>> Dependent on how parallel the build is, that can lead to tons of waiting process
>>>>> (i.e. more than your number of online cpus), which can actually hurt your build
>>>>> time.
>>>> 
>>>> I read the manual and looked at the code, which supports your statement. (I think I had some statement on stack overflow and the last time I believe anything on the internet :-) I have not seen a lot of differences in compile times with -j on my system. Mostly I suspect it is the number of paths in the dependency, cores and memory on the system.
>>>> 
>>>> I have 72 lcores or 2 sockets, 18 cores per socket. Xeon 2.3Ghz cores.
>>>> 
>>>> $ export RTE_TARGET=x86_64-native-linuxapp-gcc 
>>>> 
>>>> $ time make install T=${RTE_TARGET}
>>>> real	0m59.445s user	0m27.344s sys	0m7.040s
>>>> 
>>>> $ time make install T=${RTE_TARGET} -j
>>>> real	0m26.584s user	0m14.380s sys	0m5.120s
>>>> 
>>>> # Remove the x86_64-native-linuxapp-gcc
>>>> 
>>>> $ time make install T=${RTE_TARGET} -j 72
>>>> real	0m23.454s user	0m10.832s sys	0m4.664s
>>>> 
>>>> $ time make install T=${RTE_TARGET} -j 8
>>>> real	0m23.812s user	0m10.672s sys	0m4.276s
>>>> 
>>>> cd x86_64-native-linuxapp-gcc
>>>> $ make clean
>>>> $ time make
>>>> real	0m28.539s user	0m9.820s sys	0m3.620s
>>>> 
>>>> # Do a make clean between each build.
>>>> 
>>>> $ time make -j
>>>> real	0m7.217s user	0m6.532s sys	0m2.332s
>>>> 
>>>> $ time make -j 8
>>>> real	0m8.256s user	0m6.472s sys	0m2.456s
>>>> 
>>>> $ time make -j 72
>>>> real	0m6.866s user	0m6.184s sys	0m2.216s
>>>> 
>>>> Just the real time numbers in the following table.
>>>> 
>>>> processes     real Time   depdirs
>>>>    no -j             59.4s        Yes
>>>>      -j 8             23.8s        Yes
>>>>     -j 72            23.5s        Yes
>>>>       -j               26.5s        Yes
>>>> 
>>>>    no -j             28.5s         No
>>>>      -j 8               8.2s         No
>>>>     -j 72              6.8s         No
>>>>       -j                 7.2s         No
>>>> 
>>>> Looks like the depdirs build time on my system:
>>>> $ make clean -j
>>>> $ rm .depdirs
>>>> $ time make -j
>>>> real	0m23.734s user	0m11.228s sys	0m4.844s
>>>> 
>>>> About 16 seconds, which is not a lot of savings. Now the difference from no -j to -j is a lot, but the difference between -j and -j <cpu_count> is not a huge saving. This leads me back to over engineering the problem when ‘-j’ would work just as well here.
>>>> 
>>>> Even on my MacBook Pro i7 system the difference is not that much 1m8s without depdirs build for -j in a VirtualBox with all 4 cores 8G RAM. Compared to 1m13s with -j 4 option.
>>>> 
>>>> I just wonder if it makes a lot of sense to use cpuinfo in this given case if it turns out to be -j works with the 80% rule?
>>>> 
>>> It may, but that seems to be reason to me to just set DPDK_MAKE_JOBS=0, and
>>> you'll get that behavior
>> 
>> Just to be sure, ‘make -j 0’ is not a valid argument to the -j option. It looks like you have to do ‘-j’ or ‘-j N’ or no option where N != 0
>> 
>> I think we just use -j which gets us the 80% rule and the best performance without counting cores.
>> 
> Thats odd, specifying 0 works for me.  If it doesn't for you, specify $MAX_INT
> or some other huge number would be comparable

rkwiles@supermicro (master):~/.../dpdk/x86_64-native-linuxapp-gcc$ make --version
GNU Make 4.1
Built for x86_64-pc-linux-gnu
Copyright (C) 1988-2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

rkwiles@supermicro (master):~/.../dpdk/x86_64-native-linuxapp-gcc$ make -j 0
make: the '-j' option requires a positive integer argument

rkwiles@supermicro (master):~/.../dpdk/x86_64-native-linuxapp-gcc$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 16.04.1 LTS
Release:	16.04
Codename:	xenial

> 
> Neil
> 
>>> 
>>> Neil
>>> 
>>>> On some other project with a lot more files like the FreeBSD or Linux distro, yes it would make a fair amount of real time difference.
>>>> 
>>>> Keith
>>>> 
>>>>> 
>>>>> While its fine in los of cases, its not always fine, and with this
>>>>> implementation you can still opt in to that behavior by setting DPDK_MAKE_JOBS=0
>>>>> 
>>>>> Neil