Date: Wed, 20 Jun 2001 20:00:47 -0400 From: Sergey Babkin <babkin@bellatlantic.net> To: "Ashutosh S. Rajekar" <asr@softhome.net> Cc: Terry Lambert <tlambert2@mindspring.com>, Matt Dillon <dillon@earth.backplane.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: max kernel memory Message-ID: <3B31392F.7CEDE6C4@bellatlantic.net> References: <Pine.LNX.4.21.0106201600160.1739-100000@vangogh.indranetworks.com>
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"Ashutosh S. Rajekar" wrote: > > On Wed, 20 Jun 2001, Terry Lambert wrote: > > > Their 3200 only has 1G of RAM; you could _barely_ fit the > > TCP state for 1,000,000 connections into just 1G of RAM, > > and have a tiny amount left over for buffers, drivers, > > the rest of your kernel, etc.. I can't believe that their > > 3100 (only 512M of RAM) could do it, just based on what I > > know from the structure sizes needed for the state. You > > can fool some of the people, but you can't fool Stevens... > > Yes. One of their engineers did mention that memory management was > definitely a problem for them ... And their bragging number is also a bit > far-fetched. I bet with the 3xxx type of boxes they can't support more > than 10000 active connections, each sending/receiving 40k of dynamically > generated HTML by websites like google/altavista. My understanding (which is derived from that interview 3 years ago, with no newer information) is that Netscaler boxes don't buffer that contents, they just pass it through from and to the real servers. They also don't have to keep the full TCP state because the major thing needed from them is to change the server address in the packets plus update checksums and stuff like this. My guess is that about 40 bytes per connection should be enough (say, 2 or 3 IP address-port tuples by 6 bytes, 2 sequential numbers by 4 bytes, pointer to the target interface, pointer to the list pf packets being modified, a little bit of state and some overhead for quick searches). -SB To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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