Re: [PATCH RFC] big reader semaphore take#2

[Nick Piggin]

Tejun Heo wrote:
> Nick Piggin wrote:

> > The upshot of that would be that you could build the whole thing
> > from rwsem infrastructure and have basically zero other locking
> > mechanisms or complexity that you don't want in a synchronisation
> > primitive.
>
> To certain extent, I do agree with you - it's safer/simpler..., but on 
> the other hand, new brsem isn't that more complex and would perform 
> almost identically without extra semantical baggage.  So, I thought it 
> might be worth a bit more effort.

I would do it thisway if possible, yes.

> Hmm... So, array of rwsem's, it should be.

First implementation would be per-cpu just rwsems. A second patch
to make it just an array rwsem->count's plus a shared queue may
be in order - OTOH everyone does their own rwsems, so this will be
a bit of a headache.

I forget - are you just planning to use one global brsem? In this
case the size issue wouldn't be a pressing one.

--
SUSE Labs, Novell Inc.

Send instant messages to your online friends http://au.messenger.yahoo.com 
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/