Date: Sun, 8 Feb 2009 15:41:55 +0100 From: Bernd Walter <ticso@cicely7.cicely.de> To: Ragnar Lonn <ragnar@gatorhole.com> Cc: ticso@cicely.de, freebsd-virtualization@freebsd.org, Julian Elischer <julian@elischer.org> Subject: Re: More open sockets with vimages? Message-ID: <20090208144155.GN32126@cicely7.cicely.de> In-Reply-To: <498EE22E.7020005@gatorhole.com> References: <498DF945.3000702@gatorhole.com> <498E0797.4040002@elischer.org> <498EC554.4020905@gatorhole.com> <20090208130435.GL32126@cicely7.cicely.de> <498EE22E.7020005@gatorhole.com>
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On Sun, Feb 08, 2009 at 02:46:22PM +0100, Ragnar Lonn wrote: > Bernd Walter wrote: > >This is simple maths: > >100k Sockets with 32k TX and 64k RX buffer take 9G Memory. > >Just buffer space, not to mention socket state, ... > >On i386 this is limited by kmem, which defaults to IIRC 512MB and > >is limited by 32bit virtual address space on i386. > >On amd64 depending on the OS version you can have a kmem of slighty > >less than 2G max or several GB. > >Nevertheless you are still limited with physical RAM. > >Smaller buffers are possible, but usually people want larger buffers > >to keep up with recent line speeds. > >Today buffer sizes can be dynamic - don't know the exact details, but > >you should keep in mind that 32k/96k is already quite small for > >many purposes. > > > > But physical memory is cheap, and most low-end machines can have 16G or > more today. Is it just a matter of having enough RAM and a 64-bit OS > then? How much is "several GB [kmem]" that you mention above? AFAIK it is the only limitation - people are using 100k+ sockets since at least FreeBSD-4, but with several restrictions because of memory. It mostly depends on your application and network topology to your peers. Don't know where the current kmem limits exactly are - AFAIK kmem is hold within KVA and KVA is limited by a static map size. It has been widely discussed recently, because ZFS loves a large kmem. -- B.Walter <bernd@bwct.de> http://www.bwct.de Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.
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