Date: Tue, 18 Apr 2006 17:00:52 -0700 From: Sam Leffler <sam@errno.com> To: Mike Tancsa <mike@sentex.net> Cc: freebsd-net@freebsd.org Subject: Re: crypto accelerators Message-ID: <44457DB4.4030601@errno.com> In-Reply-To: <bjua42ds5esbkeek8v8a9qelhtbebteqm4@4ax.com> References: <200604180244.k3I2icZj076600@white.dogwood.com> <bjua42ds5esbkeek8v8a9qelhtbebteqm4@4ax.com>
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Mike Tancsa wrote: > On Mon, 17 Apr 2006 16:44:38 -1000 (HST), in sentex.lists.freebsd.net > you wrote: > >> I've read here before (or maybe some other freebsd list) that cards >> like the Soekris 1401 don't gain as much as you'd expect due to moving >> packets to/from the card over the PCI bus. But the context is usually >> one of trying to encrypt packets to increase throughput. >> >> So the question is whether these cards, regardless of their affect on >> throughput, increase usable CPU cycles? I have several Soekris 1401 >> cards and am wondering if there would be any point to putting them >> into some machines that provide logins over ssh. These machines are >> generally pretty good spec, 2.4GHz+, 1GB RAM, Intel MBs, mostly >> on-board peripherals. > > > The only place I found it really helpful for ssh connections was on > our backup server where we had multiple inbound ssh connections (e.g. > 10+ at once sending dump piped through ssh) it kept the CPU > utilization down. If you have just one or two, it doesnt really > matter Unless you're doing lots of scp's it's unlikely ssh traffic is going to generate large packets so offloading the crypto won't be worthwhile (cost to setup the h/w op probably is higher than doing the op in s/w). This has been discussed previously; see for example my BSDCan 2003 paper. Sam
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