14 Mar
2010
14 Mar
'10
4:48 a.m.
On 14.3.2010, at 4.40, Frank Cusack wrote:
Just playing devil's advocate since you haven't presented the advantage of async I/O. I don't want to guess at the reasoning, but e.g. I hope you're not planning to return success results before I/O actually completes.
The idea was that a single process could handle tons of connections. Maybe in the end the number of IMAP processes you'd have would be about 1-2 x the number of CPU cores.
And not just that. Also parallelism. Dovecot could issue a lot of I/O requests in parallel and OS can reorder those so that it gives the best performance by reading them from disk in the right order. And the higher the latency to disks is, the higher benefits there comes from parallelism (NFS, NoSQL).