Re: squid-2.5 and coss

On Wednesday 27 August 2003 11.32, Andres Kroonmaa wrote:

> Isn't block io restricted to 4/8K size anyway? Its a matter of VM
> of OS.

Depends..

raw disk block via character device is usually 512.

VM or OS may put additional page restrictions on filesystem or block
device I/O where page size is determined by CPU and OS architecture
(usually 4-16KB)

> By using raw device or O_DIRECT it becomes responsibility of app
> to ensure optimal disk access pattern.
> Now that ram has become cheap and huge disk systems fast, need for
> apps handling additional complexity is hard to justify.

Agreed in principle.

> COSS, being basically ring buffer, is very simple disk pattern and
> doesn't really benefit much from avoiding OS support, so, imo, it
> would work as well on plain FS as on any other approach. The only
> reason to go for raw disk or O_DIRECT would be if we want to keep
> ram usage to very minimum, ie for very lowend boxes.

And most OS:es can be tuned accordingly to not waste valuable memory
on filesystem buffers when memory is limited, and the OS algorithms
becomes smarter and smarter requiring less such tuning.

Regards
Henrik
Received on Wed Aug 27 2003 - 04:33:37 MDT