Date: Sat, 17 Feb 2018 09:43:21 -0700 From: Ian Lepore <ian@freebsd.org> To: bob prohaska <fbsd@www.zefox.net>, freebsd-arm@freebsd.org Subject: Re: Pi3 out of swap at < 50% Message-ID: <1518885801.91697.2.camel@freebsd.org> In-Reply-To: <20180217162732.GA93736@www.zefox.net> References: <20180217162732.GA93736@www.zefox.net>
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On Sat, 2018-02-17 at 08:27 -0800, bob prohaska wrote: > Running make -j4 buildworld on a Pi3 at r329360 tends to result > in messages similar to: > > pid 33492 (llvm-tblgen), uid 0, was killed: out of swap space > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 11764, size: 28672 > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 16080, size: 4096 > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 15721, size: 20480 > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 28139, size: 65536 > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 40544, size: 4096 > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 58384, size: 65536 > pid 49735 (c++), uid 0, was killed: out of swap space > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 28470, size: 4096 > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 24889, size: 8192 > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 28736, size: 4096 > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 29736, size: 4096 > > even though swap usage appears to be less than one GB out of two available. > > So far it's been possible to use the -DNO_CLEAN option with make to pick > up where things left off and I've backed down to -j3 to see if that helps. > > There are two 1 GB swap partitions, one on USB flash and one on the microSD > card and both appear to be in use according to swapinfo. There are no warnings > in the boot messages and no explicit changes have been made to configuration > files apart from adding the swap entries to /etc/fstab. > > World and kernel are about two weeks out of sync, so top isn't perfectly > up-to-date with this kernel; could that account for the mismatch between > apparent swap usage and the "out of swap" messages? > > Thanks for reading, and any ideas! > > bob prohaska I suspect your swap devices are too slow to keep up with instantaneous demands. An sdcard can easily have read and write latencies as big as 30 seconds; they make pretty poor swap devices (have gstat running in another window during the build to see what I mean, look at the ms/r and ms/w columns). USB flash drives may not be much better. -- Ian
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