Date: Tue, 02 Dec 1997 00:34:30 -0800 From: David Greenman <dg@root.com> To: Amancio Hasty <hasty@rah.star-gate.com> Cc: Charles Mott <cmott@srv.net>, hackers@FreeBSD.ORG Subject: Re: ftp server on ftp.cdrom.com Message-ID: <199712020834.AAA15970@implode.root.com> In-Reply-To: Your message of "Mon, 01 Dec 1997 20:50:47 PST." <199712020450.UAA01727@rah.star-gate.com>
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>> On Mon, 1 Dec 1997, Amancio Hasty Jr wrote: >> > >> > Actually, I was thinking more along the lines of state machine with >> > the functionality to share data transfers you know to avoid the >> > case of hundreds of users opening a single file N times. >> > >> > Most network engineers are familiar with an event or a state machine >> > driven network server . >> > >> > Cheers, >> > Amancio >> > >> >> Initially, I was thinking that port 20 data transfers (as opposed to port >> 21 control traffic) had to be either separate processes or threads, but >> now I think you are right -- everything could be done by a synchronous >> state machine in a single user process, but this might be inefficient. > >You can do it as you have suggested also the thing to keep in mind is the >cost of per connection and memory. For instance a process context switch >plus the over head of a process is not a very efficient mechanism for >large scale ftp servers. Oh? Are you speaking as an authority on this subject? :-) Actually, context switch overhead is not a problem. Processes in FreeBSD are fairly light weight in terms of memory as well and most of the memory is consumed by socket and disk buffers, not by the overhead of a process (at least in my implementation of ftpd). Anyway, I don't mean to squelch the conversation regarding this, but I do ask that people not make silly assumptions without first actually studying the problem. -DG David Greenman Core-team/Principal Architect, The FreeBSD Project
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