concurrent scp transfers (and a testing methodology ?)

[NicolasBérard Nault]

I think the "divide by two" methodology would be flawed because packets
would circulate on local loopback which is must faster than Ethernet. More
transferts would be possible in a long period of time because of that.

Joe Schmoe said:
>
> I have read several documents on the number of
> concurrent  https sessions a FreeBSD system is capable
> of.
>
> However, I wonder how well this relates to how many
> ssh sessions (scp file transfers, specifically) that a
> FreeBSD server can handle.  Can anyone throw out some
> basic numbers for this ?  Assuming a 1ghz p3 and 2gigs
> of RAM, and assuming that everyone is transferring a
> totally different file.  (so there is no amount of
> cache hits - everything comes straight off the drives)
>
> I would think the major bottleneck would be disk - you
> would start chugging the disks far before you used up
> all the CPU on a 1ghz p3 ... but what is the second
> bottleneck ?  Is it cpu, or is it ram (or mbufs, etc.)
>
> Would it be a reasonable test to just start up scp
> sessions from the machine to itself and then divide
> the number of sessions you can acceptably create by
> the number 2 ?  Or is this somehow a flawed test ?
>
> Any additional comments (kernel tunes, settings, war
> stories) are greatly appreciated. (like, does SMP help
> a lot here, or just a little ?)
>
>
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-- 
Nicolas Bérard Nault (nicobn at quebecbsd.org)
http://www.quebecbsd.org
http://www.xeatech.net
http://staff.xeatech.net/nicobn

"Je ne sais pas avec quelles armes se combattra la troisième guerre
mondiale mais je peux vous assurer que la quatrième se combattra avec des
pierres et des bâtons." -- Albert Einstein.



-- 
Nicolas Bérard Nault (nicobn at quebecbsd.org)
http://www.quebecbsd.org
http://www.xeatech.net
http://staff.xeatech.net/nicobn

"Je ne sais pas avec quelles armes se combattra la troisième guerre
mondiale mais je peux vous assurer que la quatrième se combattra avec des
pierres et des bâtons." -- Albert Einstein.