Date: Sun, 21 Jan 2024 06:03:39 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Warner Losh <imp@bsdimp.com> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: The Case for Rust (in the base system) Message-ID: <ZayXm34odjKKIlWp@kib.kiev.ua> In-Reply-To: <CANCZdfpDVCP2qcz6HK1HeehBkLwyRxk2pmvP0FKGax%2BMcHmxag@mail.gmail.com> References: <CAOtMX2hAUiWdGPtpaCJLPZB%2Bj2yzNw5DSjUmkwTi%2B%2BmyemehCA@mail.gmail.com> <1673801705774097@mail.yandex.ru> <CANCZdfpqWgvV_RCvVO_pvTrmajQFspW%2BQ9TM_Ok3JrXZAfeAfA@mail.gmail.com> <20240121110611.af567b0ac3a8fd8593ffcb7f@dec.sakura.ne.jp> <CAOtMX2ho7b9VOnABzdRvWn_gNmz3_V1Ac1Rmo-XRC72sPTttKQ@mail.gmail.com> <CANCZdfpDVCP2qcz6HK1HeehBkLwyRxk2pmvP0FKGax%2BMcHmxag@mail.gmail.com>
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On Sat, Jan 20, 2024 at 08:43:53PM -0700, Warner Losh wrote: > On Sat, Jan 20, 2024, 7:20 PM Alan Somers <asomers@freebsd.org> wrote: > > > On Sat, Jan 20, 2024 at 7:06 PM Tomoaki AOKI <junchoon@dec.sakurane.jp> > > wrote: > > > > > > On Sat, 20 Jan 2024 15:31:23 -0700 > > > Warner Losh <imp@bsdimp.com> wrote: > > > > > > > On Sat, Jan 20, 2024 at 11:45 AM Aleksandr Fedorov < > > wigneddoom@yandex.ru> > > > > wrote: > > > > > > > > > What about external dependencies? > > > > > > > > > > > > https://github.com/Axcient/freebsd-nfs-exporter/blob/master/Cargo.toml#L19 > > > > > > > https://github.com/asomers/gstat-rs/blob/master/gstat/src/main.rs#L20 > > > > > > > > > > Is there any plan for which crates we should take into the base > > system? > > > > > > > > > > We have had C++ in base for many years, but I don’t see any good > > libraries > > > > > for CLI, logging, JSON, etc. > > > > > > > > > > > > > > > > > https://doc.rust-lang.org/rustc/platform-support.html#tier-1-with-host-tools > > > > > > > > > > Where is the support for Freebsd as a primary platform? ARM, RISC-V, > > > > > Power? Should we rewrite devd? > > > > > > > > > > I think we need to start by providing official repositories (e.g > > > > > git.FreeBSD.org/rust.git or git.FreeBSD.org/go.git) > > > > > for different languages that include stable bindings to the system > > API: > > > > > - sysctl > > > > > - libgeom > > > > > - libifconfig > > > > > - netgraph > > > > > - jail > > > > > - etc. > > > > > > > > > > So that it’s not just some anonymous on crates.io that represents > > these > > > > > bindings, but our community. > > > > > Officially, with support for a stable ABI for releases, security > > patches, > > > > > etc. > > > > > > > > > > After this, it will be possible to think about which components to > > include > > > > > in the base system. > > > > > > > > > > I would be glad to see a more modern language than C in the > > database, but > > > > > I’m afraid that it will be like with C++, > > > > > that we will get a couple of daemons and utilities and that’s all. > > > > > > > > > > > > > These are all good questions that need good answers, though > > necessarily to > > > > get started. > > > > > > > > But the other question that occured to me after my last posting was > > "What > > > > about build integration?" > > > > How much of the rust automation do we take in vs how much do we drive > > from > > > > a future bsd.rust.mk. > > > > I can sketch out bsd.rust.mk (to pick an arbitrary name, we'd likely > > need > > > > one for what we traditionally > > > > think of as libraries (which may or may not map 1:1 onto crates: we > > could > > > > have c callable libraries > > > > written in rust in the future, for example) and one for binaries. > > > > Initially, though, if we go with the > > > > 'make rust tests possible' then we'd likely need the appropriate > > packages > > > > installed for whatever > > > > dependencies we'd have in the tests. This would give us a taste for > > what > > > > we'd need to do for > > > > base, I'd think. Once we had that notion, I can easily see there > > needing to > > > > be some sort of > > > > rust bindings for ATF/kyua as one of the first libraries / crates that > > > > would test that aspect of > > > > the build system. That all would be up to the people writing the tests > > in > > > > rust, I'd imagine. > > > > > > > > While I could jot out the basics of this integration (so one could > > just add > > > > the rust > > > > tools to a subdir or subdirs, include the bsd.rust.mk or whatever and > > then > > > > it would build > > > > if rust is enabled, and would emit a warning it was skipped because > > rust > > > > was disabled). > > > > We'd find out if this is workable or not and iterate from there. But > > that > > > > would also require > > > > active participation from the rust advocates to make it a reality: I > > can > > > > put together the > > > > build infrastructure for the disabled case, but likely can't on my own > > do > > > > the rust enabled > > > > case. I'd be happy to work with someone to do that, but I'm not going > > to be > > > > able to do > > > > that myself: my need for rust is slight, my knowledge of rust is weak, > > etc. > > > > Working with > > > > someone (or ideally several someones), though it could become reality. > > So > > > > please contact > > > > me if you'd like to work on this. > > > > > > > > Warner > > > > > > One way to go could be moving programs rewritten with rust to ports. > > > There are some programs (not in rust, though) moved to ports, like rcs. > > > > I've already done this with a few, though I didn't delete the C > > versions from base. > > usr.bin/gstat => sysutils/gstat-rs > > tools/regression/fsx => devel/fsx > > > > So > % size `which gstat-rs` `which gstat` > text data bss dec hex filename > 2094442 176472 568 2271482 0x22a8fa /usr/local/sbin/gstat-rs > 19350 1180 41 20571 0x505b /usr/sbin/gstat > % file `which gstat-rs` `which gstat` > /usr/local/sbin/gstat-rs: ELF 64-bit LSB pie executable, ARM aarch64, > version 1 (FreeBSD), dynamically linked, interpreter /libexec/ld-elf.so.1, > FreeBSD-style, stripped > /usr/sbin/gstat: ELF 64-bit LSB pie executable, ARM aarch64, > version 1 (FreeBSD), dynamically linked, interpreter /libexec/ld-elf.so.1, > for FreeBSD 15.0 (1500008), FreeBSD-style, stripped > 8:36pm brazos:[3826]> ldd `which gstat-rs` `which gstat` > /usr/local/sbin/gstat-rs: > libgeom.so.5 => /lib/libgeom.so.5 (0x60fd38647000) > libthr.so.3 => /lib/libthr.so.3 (0x60fd38b57000) > libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x60fd39af1000) > libc.so.7 => /lib/libc.so.7 (0x60fd3be6f000) > libbsdxml.so.4 => /lib/libbsdxml.so.4 (0x60fd3a009000) > libsbuf.so.6 => /lib/libsbuf.so.6 (0x60fd3a55e000) > /usr/sbin/gstat: > libdevstat.so.7 => /lib/libdevstat.so.7 (0x448867cd000) > libgeom.so.5 => /lib/libgeom.so.5 (0x4488710b000) > libedit.so.8 => /lib/libedit.so.8 (0x44887f8d000) > libtinfow.so.9 => /lib/libtinfow.so.9 (0x44888aab000) > libncursesw.so.9 => /lib/libncursesw.so.9 (0x44889c60000) > libc.so.7 => /lib/libc.so.7 (0x4488aaf4000) > libkvm.so.7 => /lib/libkvm.so.7 (0x44888f77000) > libbsdxml.so.4 => /lib/libbsdxml.so.4 (0x4488ba02000) > libsbuf.so.6 => /lib/libsbuf.so.6 (0x4488c68d000) > libelf.so.2 => /lib/libelf.so.2 (0x4488ca45000) > > So that looks scary, like rust is 100x larger binaries... But at runtime > it's about the same: > USER PID %CPU %MEM VSZ RSS TT STAT STARTED TIME COMMAND > imp 14735 0.0 0.0 14140 4828 0 S+ 20:38 0:00.04 gstat > imp 14766 1.3 0.0 15772 6256 0 S+ 20:39 0:00.02 gstat-rs > > So the runtime size is at least in the same ballpark (still larger, but not > crazy larger). More CPU too, > but that's just a polling artifact I think (other times gstat had some, and > gstat-rs didn't). > > Why is the rust binary so much larger? Are the rust runtime and > dependencies statically linked? Simple answer is yes. More complete answer is that nobody, practically speaking, writes a program in Rust + standard library. It is always several dozens of crates that are often indeed useful, and which bring up their own dependencies. All of that stuff is statically linked into the binary, remember that Rust does not have stable ABI. For some parts of the language, like async, you must use huge external dependencies, importing which into the base system is not practical (I do not mean a compiler, which seems to be already agreed not to). Also Rust-generated code seems to be fatter than corresponding C, not least because value-passing is much more common in Rust. Looking at disassembly the dominating theme are memory moves.
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