On Thu, Jul 21, 2016 at 02:09:19PM +0000, Wiles, Keith wrote: > > > On Jul 21, 2016, at 8:54 AM, Neil Horman <nhorman at 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 at 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 at 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 at 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
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 >