[Lustre-discuss] short writes

[Andrew Perepechko]

Hello John.

On 07/16/2010 01:21 AM, John Hammond wrote:
> A sockets isn't considered "slow" because of the speed of the network,
> it's considered "slow" so that the application is allowed to handle
> IPC with unresponsive peers.
>
The Linux man page does not state that socket I/O is considered "slow"
NOT because of the speed of the network. It is usually considered slow
because of possible slowness of the network and because of possible
unresponsive peers and some other reasons. In any case, the difference
between the local disk I/O and the socket I/O is not that the latter may
last forever since the socket interface uses the notion of timeout.
Also, local disk I/O may take very long time to complete if the I/O
subsystem is under pressure. The difference is subtle.

If possible unresponsive peers indicate "slowness" of the I/O, then
Lustre client _should_ be able to interrupt the I/O and is allowed
perform short reads.

Best wishes,
Andrew.