From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.tuxdriver.com (charlotte.tuxdriver.com [70.61.120.58]) by dpdk.org (Postfix) with ESMTP id E85775584 for ; Thu, 21 Jul 2016 15:54:50 +0200 (CEST) Received: from cpe-2606-a000-111b-40ed-7aac-c0ff-fec2-933b.dyn6.twc.com ([2606:a000:111b:40ed:7aac:c0ff:fec2:933b] helo=localhost) by smtp.tuxdriver.com with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.63) (envelope-from ) id 1bQEQy-0001Xv-1g; Thu, 21 Jul 2016 09:54:44 -0400 Date: Thu, 21 Jul 2016 09:54:33 -0400 From: Neil Horman To: "Wiles, Keith" Cc: Neil Horman , Thomas Monjalon , "dev@dpdk.org" , "Mcnamara, John" Message-ID: <20160721135433.GA9628@hmsreliant.think-freely.org> References: <1469034588-1847-1-git-send-email-nhorman@tuxdriver.com> <6330653.K6A9CLrOZy@xps13> <20160720174849.GE28844@hmsreliant.think-freely.org> <20160720201617.GA23515@hmsreliant.think-freely.org> <9309C1B3-D86C-4265-97A4-58E3D7958944@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9309C1B3-D86C-4265-97A4-58E3D7958944@intel.com> User-Agent: Mutt/1.6.2 (2016-07-01) X-Spam-Score: -1.0 (-) X-Spam-Status: No Subject: Re: [dpdk-dev] [PATCH] validate_abi: build faster by augmenting make with job count X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Jul 2016 13:54:51 -0000 On Wed, Jul 20, 2016 at 10:32:28PM +0000, Wiles, Keith wrote: > > > On Jul 20, 2016, at 3:16 PM, Neil Horman wrote: > > > > On Wed, Jul 20, 2016 at 07:47:32PM +0000, Wiles, Keith wrote: > >> > >>> On Jul 20, 2016, at 12:48 PM, Neil Horman wrote: > >>> > >>> On Wed, Jul 20, 2016 at 07:40:49PM +0200, Thomas Monjalon wrote: > >>>> 2016-07-20 13:09, Neil Horman: > >>>>> From: Neil Horman > >>>>> > >>>>> 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 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 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 > > > >> >