Date: Wed, 28 Feb 2018 14:37:36 -0500 From: Mike <the.lists@mgm51.com> To: bob prohaska <fbsd@www.zefox.net> Cc: freebsd-arm@freebsd.org Subject: Re: Is maximum swap usage tunable? Message-ID: <8f422161-885e-aa91-eacd-018540222d65@mgm51.com> In-Reply-To: <20180228185517.GB26187@www.zefox.net> References: <20180228170311.GA26187@www.zefox.net> <a759ecea-83f4-b0b2-7113-c39633f68637@mgm51.com> <20180228185517.GB26187@www.zefox.net>
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On 2/28/2018 1:55 PM, bob prohaska wrote: > On Wed, Feb 28, 2018 at 12:20:56PM -0500, Mike wrote: >> On 2/28/2018 12:03 PM, bob prohaska wrote: >>> In watching system compilations on an RPi3 it looks as if the >>> system starts killing processes with "out of swap" warnings >>> well below 50% of full utilization (in this case, 2 GB). One >>> recent instance of make -j4 kernel-toolchain killed llvm-tblgen >>> with only 34% of the swap in use. >>> >>> Is the maximum swap usage limit adjustable in any way? I didn't >>> recognize anything useful in the page at >>> https://www.freebsd.org/cgi/man.cgi?query=sysctl(8)&sektion=&manpath=freebsd-release-ports >>> >>> It's possible the problem is really swap speed, rather than size, so I'd >>> like to try changing size limits if possible. The swap media claims 2-3 >>> MB/sec random write speed and observations with gstat seem to support the >>> claim, but transient stalls are hard to observe. An RPi2 with similar >>> hardware seems to have no problems. >>> >> >> >>> It's possible the problem is really swap speed >> >> I was running into swap speed / timeout issues. There were messages on >> the console to that effect. >> >> Once I put the swap space on rotating rust, that part of the compile >> problem disappeared. I use 1GB swap space. >> > > The latest kernel versions seem to have largely done away with the > "indefinite wait buffobj" warnings. They're few and far between, > the compile proceeds unless they're abundant. The fact that armv7 > has no problem, and the system is reporting "out of swap" with 34% > in use strikes me as suspicious. Kernel and userland are in sync, > so the figure of 34% swap usage is probably accurate. > > Perhaps my question is better phrased thus: How does FreeBSD-arm > determine when it's out of swap? > Thanks for the follow-up. I was planning to download and try the RPI3-20180226-r330034 image file this evening. Per your comment, I'll not use the rusty swap space, and see what happens. I'll report back, probably on the morrow... thx.home | help
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