On 1 November 2015 at 20:05, Jeff Roberson <jrober...@jroberson.net> wrote: > On Sun, 1 Nov 2015, NGie Cooper wrote: > >> >>> On Nov 1, 2015, at 19:20, Adrian Chadd <adrian.ch...@gmail.com> wrote: >>> >>> hiya jeff, >>> >>> this broke low-memory, no-swap boards (eg MIPS.) >>> >>> On a MIPS board (carambola2) with 32MB of RAM, just scp'ing a kernel >>> into the rootfs on USB hangs the system. After doing some digging, I >>> found this: >>> >>> >>> INTERNAL: Allocating one item from buf free cache(0x83fea7e0) >>> uma_zalloc_arg: Bucketzone returned NULL >>> INTERNAL: Allocating one item from buf free cache(0x83fea7e0) >>> uma_zalloc_arg: Bucketzone returned NULL >>> >>> .. and it was just stuck in a loop trying to allocate them, failing, >>> and trying to allocate them again. >>> >>> I'll see if I can reproduce it with a qemu emulator with sufficiently >>> low RAM so you don't need a MIPS router to reproduce it. >>> >>> It's sufficient to just start the scp; it runs out of RAM within a >>> couple of seconds. >>> >>> Any ideas? >> >> >> What happens if you change vfs.maxbufspace ? >> >> The reason that I?m noting is that (if I?m reading the code correctly), >> it?s now allocating 16 clean queues instead of 1 and each is up to >> vfs.maxbufspace size, which is 256MB per queue based on this line: >> >> + clean_queues = MIN(howmany(maxbufspace, 256*1024*1024), CLEAN_QUEUES); >> >> The 256MB amount seems like it should be a tunable, as well as the >> CLEAN_QUEUES #define? it?s a bit high for low memory platforms, i.e. >> platforms with <372MB of scratch space to play around with I?m guessing? > > > maxbufspace is still a global. It just makes N queues for every 256MB of > configured buffer cache size. > > We shouldn't be looping forever. It should sleep and try to re-allocate. > How many cpus are on the mips board? We may need to implement something to > directly flush the buf zone and disable the per-cpu caches when allocation > fails.
It's a single CPU mips board (AR9331 SoC.) -adrian _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
