Re: Async I/O on IRIX 6.x?

From: Alex Rousskov <>
Date: Tue, 1 Sep 1998 16:52:13 -0600 (MDT)

On Tue, 1 Sep 1998, Duane Wessels wrote:

> Has anyone gotten asyncronous I/O to work on IRIX 6.x?

More precisely, has anyone gotten asynchronous I/O to work better than
synchronous I/O on IRIX 6.x? :)

If there are async/IRIX gurus out there, here is what we have:

        40 simulated clients, each submitting requests as soon as
                they get reply,
        1 simulated server
        no hits
        all requests cachable
        no persistent connections

The configuration gets about 500req/sec thru a null-proxy. (Null-proxy runs
on the same machine and just forwards requests to the server and replies to
the clients).

When Squid 1.2 replaces our null-proxy and starts with an empty cache, we
get about 30req/sec for sync-io and 12 req/sec for async-io.

All these numbers are preliminary, but the sync/async difference is already
obvious and disturbing.

Async-io always complains about NUMTHREADS being too low (currently 128, tried
16, 32, and 64). The distribution of waiting threads may look like this:

Queue Length = 2278

               # %
       OPEN 378 16.59
       READ 0 0.00
      WRITE 804 35.29
      CLOSE 1096 48.11

#reads is always 0. #close is always close to 50%.

Any clues? What tools are async-people using to debug threads performance?


Received on Tue Sep 01 1998 - 15:53:40 MDT

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