On 30.05.2019 13:22, Bruce Richardson wrote: > On Wed, May 29, 2019 at 09:37:20PM +0100, Luca Boccassi wrote: >> On Wed, 2019-05-29 at 19:39 +0300, Ilya Maximets wrote: >>> The first thing many developers do before start building DPDK is >>> disabling all the not needed divers and libraries. This happens >>> just because more than a half of DPDK dirvers and libraries are not >>> needed for the particular reason. For example, you don't need >>> dpaa*, octeon*, various croypto devices, eventdev, etc. if you're >>> only want to build OVS for x86_64 with static linking. >>> >>> By disabling everything you don't need, build speeds up literally 10x >>> times. This is important for CI systems. For example, TravisCI wastes >>> 10 minutes for the default DPDK build just to check linking with OVS. >>> >>> Another thing is the binary size. Number of DPDK libraries and, >>> as a result, size of resulted statically linked application decreases >>> significantly. >>> >>> Important thing also that you're able to not install some >>> dependencies >>> if you don't have them on a target platform. Just disable >>> libs/drivers >>> that depends on it. Similar thing for the glibc version mismatch >>> between build and target platforms. >>> >>> Also, I have to note that less code means less probability of >>> failures and less number of attack vectors. >>> >>> This patch gives 'meson' the power of configurability that we >>> have with 'make'. Using new options it's possible to enable just >>> what you need and nothing more. >>> >>> For example, following cmdline could be used to build almost minimal >>> set of DPDK libs and drivers to check OVS build: >>> >>> $ meson build -Dexamples='' -Dtests=false -Denable_kmods=false \ >>> -Ddrivers_bus=pci,vdev \ >>> -Ddrivers_mempool=ring \ >>> -Ddrivers_net=null,virtio,ring \ >>> -Ddrivers_crypto=virtio \ >>> -Ddrivers_compress=none \ >>> -Ddrivers_event=none \ >>> -Ddrivers_baseband=none \ >>> -Ddrivers_raw=none \ >>> -Ddrivers_common=none \ >>> >>> -Dlibs=kvargs,eal,cmdline,ring,mempool,mbuf,net,meter,\ >>> ethdev,pci,hash,cryptodev,pdump,vhost \ >>> -Dapps=none >>> >>> Adding a few real net drivers will give configuration that can be >>> used >>> in production environment. >>> >>> Looks not very pretty, but this could be moved to a script. >>> >>> Build details: >>> >>> Build targets in project: 57 >>> >>> $ time ninja >>> real 0m11,528s >>> user 1m4,137s >>> sys 0m4,935s >>> >>> $ du -sh ../dpdk_meson_install/ >>> 3,5M ../dpdk_meson_install/ >>> >>> To compare with what we have without these options: >>> >>> $ meson build -Dexamples='' -Dtests=false -Denable_kmods=false >>> Build targets in project: 434 >>> >>> $ time ninja >>> real 1m38,963s >>> user 10m18,624s >>> sys 0m45,478s >>> >>> $ du -sh ../dpdk_meson_install/ >>> 27M ../dpdk_meson_install/ >>> >>> 10x speed up for the user time. >>> 7.7 times size decrease. >>> >>> This is probably not much user-friendly because it's not a Kconfig >>> and dependency tracking in meson is really poor, so it requires >>> usually few iterations to pick correct set of libraries to satisfy >>> all dependencies. However, it's not a big deal. Options intended >>> for a proficient users who knows what they need. >> >> Hi, >> >> We talked about this a few times in the past, and it was actually one >> of the design goals to _avoid_ replicating the octopus-like config >> system of the makefiles. That's because it makes the test matrix >> insanely complicated, not to mention the harm to user friendliness, >> among other things. >> >> If someone doesn't want to use a PMD, they can just avoid installing it >> - it's simple enough. >> >> Sorry, but from me it's a very strong NACK. >> > I would agree with this position - tracking the dependencies of the > libraries etc. is a nightmare, and requires lots of ifdef'ery in the code > for handling cases where libraries don't exist. > > However, I might be ok with limiting the drivers somewhat, since they don't > tend to depend on each other so much, though ideally I'd still prefer to > have one build of DPDK that has minimal configuration. If we say that we > can disable some drivers, though, issue then becomes whether e.g. the bus > drivers could selectively be disabled, and the knock-on effects of that. > I'd hate to see the case where we end up having the meson.build files for > drivers becoming a massive list of conditional checks for a bunch of > internal dependencies. If someone is wanting to do a custom build of DPDK, > they can always patch out the subdirectories they don't want in the > meson.build files - but because of testing matrixes for such > configurations, I don't think its something we want to explicitly support.
Thanks Bruce. I see your point. Please, take a look at the first patch of this series. It doesn't directly connected to this one, but should speed up meson configuration a bit. Best regards, Ilya Maximets.
