Date: Fri, 28 Jul 2006 20:02:54 -0400 From: "Raymond Owens" <owensr@comcast.net> To: <freebsd-performance@freebsd.org> Subject: Re: question concerning proper usage of kernel variables net.bpf.bufsize and vm_kmem_size_max Message-ID: <003801c6b2a2$5b6687d0$0501a8c0@desky64>
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This is a multi-part message in MIME format. ------=_NextPart_000_0034_01C6B280.D06202C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sir, By hardware cache size, you are referring to the processor cache? If the = box has two processors, should the value used for cache size in this = calculation be doubled? In very general terms, what is the link between = the net.bpf.bufsize and the cache? Thanks for info.. R. B. Riddick wrote: >--- Raymond Owens <owensr@comcast.net> wrote: > =20 > >>Questions: >>Can VM_KMEM_SIZE_MAX be set manually with sysctl? >> >> =20 >> >No, but you could set it with this procedure: >1. Insert the lines > vm.kmem_size=3D123456789 > vm.kmem_size_max=3D1234567890 >in > /boot/loader.conf > >2. reboot > >That should change those values... >(see src/sys/kern/kern_malloc.c) > >I wonder, why your box needs such a big buffer? Do u have network = traffic >bursts or so? > =20 > Regardless what purpose is for, the net.bpf.bufsize should never set above hardware cache size. The best (optimal size) is 50% - 80% of the hardware cache size, unless original BPF is modified in some way I do not know. Such high bufsize will degrade performance. --=20 ------------ Jin Guojun ----------- v --- jin@george.lbl.gov --- Distributed Systems Department http://www.dsd.lbl.gov/~jin Lawrence Berkeley National Laboratory, Berkeley, CA 94720 ------=_NextPart_000_0034_01C6B280.D06202C0--
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