Date: Sun, 1 Nov 2015 19:29:28 -0800 From: NGie Cooper <yaneurabeya@gmail.com> To: Adrian Chadd <adrian.chadd@gmail.com> Cc: Jeff Roberson <jeff@freebsd.org>, Mark Johnston <markj@freebsd.org>, Warner Losh <imp@bsdimp.com>, benno <benno@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r289279 - in head/sys: kern vm Message-ID: <DFF7EA25-64EA-44BB-BC0D-A84E52587B9D@gmail.com> In-Reply-To: <CAJ-Vmon2kKCMp6OemhW6CKUJ_a2iKz0pGg0zG2oqy2FuvLR73w@mail.gmail.com> References: <201510140210.t9E2A79H056595@repo.freebsd.org> <CAJ-Vmon2kKCMp6OemhW6CKUJ_a2iKz0pGg0zG2oqy2FuvLR73w@mail.gmail.com>
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> On Nov 1, 2015, at 19:20, Adrian Chadd <adrian.chadd@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… Thanks, -NGie
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