On Mon, Aug 25, 2014 at 8:37 AM, Gregory Szorc <g...@mozilla.com> wrote:
> On 8/22/14 9:08 AM, Ehsan Akhgari wrote: > >> Unfortunately I don't really understand the reasons behind this, but if >> you >> use this command, please know that it doesn't work properly any more, even >> if it seems to work in some cases. AFAICT the workarounds are either >> doing >> a full build or ./mach build binaries (I don't really know what things the >> latter supports these days.) >> >> Please see https://bugzilla.mozilla.org/show_bug.cgi?id=1055204 for the >> discussion about this. >> > > I'd like to re-frame this a bit. > > How fast do "no-op" / light builds need to be for |mach build > <subdirectory>| to not exist? > > The reason people do partial builds is because the full tree build isn't > fast enough: if full tree builds completely instantaneously, we wouldn't > need partial tree builds. People like |mach build binaries| because it's > fast and gets the job done. Regular no-op builds currently take ~50s on my > MBP. That's ~50s of overhead. We can do better. > > As a build peer, partial tree builds are a thorn in my side. We have to > consider and try to support them. It's non-trivial. I'd prefer if they were > unsupported and went away. > > What amount of overhead for full builds is tolerable before we can > officially kill support for partial builds? While I'd like to say we can > deliver "instantaneous," that's not realistic unless we actively invest in > it. I wrote patches over the weekend that decrease no-op builds from ~50s > to ~37s. It's noticeably faster. I think we could get it down to 20s with a > few days of work. 10s with a few weeks of work. Any faster will likely > require a non make-based build backend. > > I'm going to say that 15s no-op build times is fast enough that we can > kill partial tree building support, or at least cripple it so it doesn't do > so much. Keep in mind that |mach build binaries| today is ~6.5s, and that's > without modifications. Modify a .cpp file affecting libxul and you are up > to ~12.5s. I experience much longer build times on my Macbook Air: A no-op ./mach build binaries is 44 seconds. In order for me to be willing to give up partial builds, this would need to be down towards 5 seconds. -Ekr _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
