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Date: Thu, 21 Jul 2016 14:34:01 -0400
From: Neil Horman <nhorman@redhat.com>
To: "Wiles, Keith" <keith.wiles@intel.com>
Cc: Neil Horman <nhorman@tuxdriver.com>,
Thomas Monjalon <thomas.monjalon@6wind.com>, "dev@dpdk.org" <dev@dpdk.org>,
"Mcnamara, John" <john.mcnamara@intel.com>
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Subject: Re: [dpdk-dev] [PATCH] validate_abi: build faster by augmenting
make with job count
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On Thu, Jul 21, 2016 at 03:22:45PM +0000, Wiles, Keith wrote:
>
> > 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
>
I'm not saying your variant doesn't work, only that my copy of make does, but
its possible that I have some alternately patched version (I used to fix make
bugs way back when, so I may have an impure copy). Regardless, my comment is
still valid, if you want to have unlimited jobs, you can just export
DPDK_MAKE_JOBS=<some very large number>
Neil
> >
> > 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
>