Date: Thu, 25 Feb 2010 17:29:19 +0200 From: David Naylor <naylor.b.david@gmail.com> To: David Naylor <naylor.b.david@gmail.com>, freebsd-hackers@freebsd.org Subject: Re: [Proof of Concept] Stacked unionfs based 'tinderbox' Message-ID: <b53f6f941002250729ide68ffdp4c38c3803d9c8a3a@mail.gmail.com> In-Reply-To: <20100225135303.GM57731@acme.spoerlein.net> References: <b53f6f941002250008mbe82d46m68ea304359d16203@mail.gmail.com> <20100225135303.GM57731@acme.spoerlein.net>
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On 25 February 2010 15:53, Ulrich Spörlein <uqs@freebsd.org> wrote: > On Thu, 25.02.2010 at 10:08:15 +0200, David Naylor wrote: >> Hi, >> >> As some may have noticed on -current I have been working on using >> stacked unionfs to implement a 'tinderbox' type build system. I have >> successfully used the scripts to build x11/xorg (and have compared the >> results to using the traditional approach using pkg_add). The build >> system is stable except for one nasty corner case: deadlocks. > > When I did this a couple of years ago, the major problems were failing > chdir(2) calls during ports build, etc. > >> To setup a compatible test environment requires: >> - recompile the kernel with `options KSTACK_PAGES=32`, otherwise the >> kernel will panic with a double fault. WITNESS options results in >> substantial performance degradation. >> - patch mtree (see below) [optional] >> - create the appropriate chroot environment (and reboot) [see below >> for corner case] >> >> A performance bottleneck in mtree was identified. This resulted in >> mtree (as run by port install) consuming ~20% of the build time. See >> bin/143732 for a patch and further details. > > Good work! > >> The normal tinderbox approach takes ~80% more time to install compared to the >> quick and dirty approach. The stacked unionfs approach takes ~170% more time >> (an increase of ~50% over the tinderbox approach). Some performance gains can >> be had if one uses memory backed storage (vs HDD in this case). > > Please explain: what is the quick and dirty approach and which one is > faster now? The quick and dirty is `make -C /usr/ports/x11/xorg install clean`. The stacked unionfs is still the slowest (even with a 20% improvement from patching mtree). > As your scripts did not make it through, perhaps you can upload them to > the wiki? What I did back then was using a clean base system as the > underlying unionfs store to avoid re-generating the clean base over and > over again. Nowadays, a ZFS clone would probably be the way to go. > > I'm not sure if a recursive approach is feasible here, as you can have > only one underlying unionfs mount. But special casing, e.g., perl may > still give a massive speedup. So for each port that has perl as > dependancy, you would not pull in the clean base + pkg_add perl, but > instead grab the clean-base+perl directory as an underlying unionfs. > > Cheers > Uli >
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