Date: Sat, 20 Mar 2010 11:22:04 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: "C. P. Ghost" <cpghost@cordula.ws> Cc: FreeBSD-Current <freebsd-current@freebsd.org>, freebsd-arch@freebsd.org Subject: Re: Increasing MAXPHYS Message-ID: <201003201822.o2KIM4xw004251@apollo.backplane.com> References: <4BA4E7A9.3070502@FreeBSD.org> <201003201753.o2KHrH5x003946@apollo.backplane.com> <d74eb87c1003201113q21ddde15nea6dc77be22ce846@mail.gmail.com>
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:Pardon my ignorance, but wouldn't so much KVM make small embedded
:devices like Soekris boards with 128 MB of physical RAM totally unusable
:then? On my net4801, running RELENG_8:
:
:vm.kmem_size: 40878080
:
:hw.physmem: 125272064
:hw.usermen: 84840448
:hw.realmem: 134217728
KVM != physical memory. On i386 by default the kernel has 1G of KVM
and userland has 3G. While the partition can be moved to increase
available KVM on i386 (e.g. 2G/2G), it isn't recommended.
So the KVM reserved for various things does not generally impact
physical memory use.
The number of swap buffers (nswbuf) is scaled to 1/4 nbufs with a
maximum of 256. Systems with small amounts of memory should not be
impacted.
The issue w/ regards to KVM problems on i386 is mostly restricted to
systems with 2G+ of ram where the kernel's various internal parameters
are scaled to their maximum values or limits. On systems with less ram
the kernel's internal parameters are usually scaled down sufficiently
that there is very little chance of the kernel running out of KVM.
-Matt
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