CIFS read-ahead

[David Collier-Brown -- Customer Engineering]

Nicholas M. Kirsch wrote:
>>   I have done some work in this area, primarily to deal
>>with filesystems which want quite large, aligned reads.
>>Notably RAID disk arrays!
>>   Can you describe your application to us? The cache read
>>code **might** address your problem.
> 
> 
> I have a very large (several terabyte) filesystem and I want good
> single-stream read performance from it. The applications which do this are
> many, including media streaming and simple file access in a single-stream
> linear fashion.

Interseting; Steve French at IBM is also working on sibgle-stream
performance, but at the Linux level...


> I am working on a NAS appliance, which uses Samba 3.0 to provide CIFS
> access to its content. Will your cache read code instruct the client to
> read-ahead? What appears to happen is the CIFS client sends a read
> request, and waits for the answer before sending another. In this
> scenario, throughput will be limited by latency. It appears as if NFS gets
> around this by sending multiple read requests at a single time.
> 
> I am not sure whether CIFS supports such things, just hoping.

	Alas, what I was doing was filesystem read-ahead, so that
	Samba's latency in delivering the single threaded,
	stop-and-wait stream was as small as possible.

--dave
-- 
David Collier-Brown,           | Always do right. This will gratify
Sun Microsystems DCMO          | some people and astonish the rest.
Toronto, Ontario               |
(905) 415-2849 or x52849       | davecb at canada.sun.com