Re: [Xenomai] rehashing

[Philippe Gerum <rpm@xenomai.org>]

On 12/16/2013 09:05 AM, Gilles Chanteperdrix wrote:
>
> Hi Philippe,
>
> looking at the registry code, I had an idea: we could increase the
> number of descriptors dynamically when they are exhausted, and increase
> the hash size as well. This would make the configurable number of slots
> a starting point, but not a liimit. The access to the registry by name
> does not really need to be fast, so we could protect it with a mutex

The registry hash is a low contention resource, so using a dedicated 
mutex is likely more efficient than grabbing the big nklock in most 
cases anyway.

> (that would mean that all services accessing the registry by name would
> need to run in secondary mode, but I am not sure we care, and if we do,
> we can use an xnsynch instead).
>
> What do you think?
>

Recent Cobalt users of the registry put aside, this is basically about 
deciding whether:

- issuing connect() on a rtipc socket should switch the caller to 
secondary mode, since other in-kernel users disappeared during the Great 
Refactoring (tm). bind() does have such requirement already.

- all present and future callers of xnregistry_remove() should run in 
secondary mode as well. There is only one caller remaining so far, and 
it does (i.e. thread cleanup code).

-- 
Philippe.