Date: Fri, 3 Jul 2020 18:15:58 -0700 From: bob prohaska <fbsd@www.zefox.net> To: Peter Jeremy <peter@rulingia.com> Cc: freebsd-arm@freebsd.org, bob prohaska <fbsd@www.zefox.net> Subject: Re: 1341MB swap in use with half gig of free memory Message-ID: <20200704011558.GA36886@www.zefox.net> In-Reply-To: <20200703233938.GB30039@server.rulingia.com> References: <20200703224433.GA36511@www.zefox.net> <20200703233938.GB30039@server.rulingia.com>
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On Sat, Jul 04, 2020 at 09:39:38AM +1000, Peter Jeremy wrote: > > The "every few minutes ... one core reaches 100%" implies that every few > minutes one process manages to get hold of enough RAM to work through a > compiling a file. That process then exits and all the RAM it was using > returns to the free pool. > That's one point I was entirely missing. When the only runnable thread finishes, nothing else can run till a working set has been swapped back into ram. As Mark reminds me, at 2MB a second, it easily takes minutes of doing nothing but reading swap to be able to run anything. Thus, the long interval of seeming inactivity. > > I don't think so. The default "run one build process per core" assumes > that there's adequate RAM. It's really difficult for the build process > to know how big a process will get, and so automatically cut back on the > number of parallel processes it spawns. This is one case where I don't > believe there is any alternative to manually specifying "-j1" or > equivalent. > In this case (essentially that of a batch job with no interactive use) would using -j1 or -j2 reduce the overall compilation time? If I'm understanding correctly the answer is "no", -j1 precludes using extra cores when it's possible. From time to time it uses all four. > Note that Chromium is a massive chunk of code. A more normal build > environment would be several dozen quite fast cores with around 3GB RAM > per core. You are really stressing the VM system by trying to build it > with ~256MB/core. > A smaller browser would be a very welcome discovery. So far, chromium is the only one that has worked well enough to be useful. Thanks for writing.... bob prohaska
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