Date: Sun, 6 Jan 2008 22:33:19 +0000 (GMT) From: Robert Watson <rwatson@FreeBSD.org> To: Kris Kennaway <kris@FreeBSD.org> Cc: freebsd-current@freebsd.org, Vadim Goncharov <vadimnuclight@tpu.ru> Subject: Re: When will ZFS become stable? Message-ID: <20080106223153.V72782@fledge.watson.org> In-Reply-To: <47814B53.50405@FreeBSD.org> References: <fll63b$j1c$1@ger.gmane.org> <20080104163352.GA42835@lor.one-eyed-alien.net> <9bbcef730801040958t36e48c9fjd0fbfabd49b08b97@mail.gmail.com> <200801061051.26817.peter.schuller@infidyne.com> <9bbcef730801060458k4bc9f2d6uc3f097d70e087b68@mail.gmail.com> <4780D289.7020509@FreeBSD.org> <flqmbo$eac$1@ger.gmane.org> <4780E546.9050303@FreeBSD.org> <9bbcef730801060651y489f1f9bw269d0968407dd8fb@mail.gmail.com> <4780EF09.4090908@FreeBSD.org> <flr0ie$euj$1@ger.gmane.org> <47810BE3.4080601@FreeBSD.org> <flr2lr$kph$1@ger.gmane.org> <4781113C.3090904@FreeBSD.org> <opt4i0g3k44fjv08@nuclight.avtf.net> <47814B53.50405@FreeBSD.org>
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On Sun, 6 Jan 2008, Kris Kennaway wrote: > Vadim Goncharov wrote: >> 06.01.08 @ 23:34 Kris Kennaway wrote: >> >>>> What is the other 512 MB of the 1 GB used for? >>> >>> Everything else that the kernel needs address space for. Buffer cache, >>> mbuf allocation, etc. >> >> Aren't they allocated from the same memory zones? I have a router with 256 >> Mb RAM, it had a panic with ng_nat once due to exhausted kmem. So, what >> these number from it's sysctl do really mean? >> >> vm.kmem_size: 83415040 >> vm.kmem_size_max: 335544320 >> vm.kmem_size_scale: 3 >> vm.kvm_size: 1073737728 >> vm.kvm_free: 704638976 > > I believe that mbufs are allocated from a separate map. In your case you > only have ~80MB available in your kmem_map, which is used for malloc() in > the kernel. It is possible that ng_nat in combination with the other kernel > malloc usage exhausted this relatively small amount of space without mbuf > use being a factor. Actually, with mbuma, this has changed -- mbufs are now allocated from the general kernel map. Pipe buffer memory and a few other things are still allocated from separate maps, however. In fact, this was one of the known issues with the introduction of large cluster sizes without resource limits: address space and memory use were potentially unbounded, so Randall recently properly implemented the resource limits on mbuf clusters of large sizes. Robert N M Watson Computer Laboratory University of Cambridge
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