Damien Miller wrote:
> On Fri, 26 Jan 2007, Chris Rapier wrote:
>
>
>>I was wondering if the disk I/O in OpenSSH is synchronous or
>>asynchronous. If its not asynchronous is there any reason why doing at
>>least asynch writes would be a bad idea? I'm just wondering if I'm over
>>looking some obvious problem.
>
>
> What disk IO? Do you mean sftp/scp?
Yes. Mostly I'm wondering if a momentary hiccup on I/O could cause a
stoppage along the entire IO chain and end up causing a delayed ACK
which might push the connection back into slow start. Even with a
reasonably fast disk on a fat enough connection seek time can exceed RTT
and sometimes by several multiples. This just came up at a meeting at
work and I had no worthwhile answer for them so I'm doing a little
research. My feeling is that HW disk buffering will prevent it from
being a factor in 99% of the time. However, I thought I would ask.
_______________________________________________
openssh-unix-dev mailing list
openssh-unix-dev@mindrot.org
http://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
|