On Thu, Sep 01, 2005 at 02:09:19PM -0400, Alan Stern wrote: > Patrick and Greg: > > To put it baldly: Should klists be replaced with regular lists, each > protected by an rwsem (or even a mutex)? > > The advantage of klists is that threads can remove or add nodes while > other threads iterate through the list. With an rwsem, only one thread > would be able to add or remove a node at a time, and only when no other > thread was using the list. Considering that klists are currently used > to hold: > > the set of all devices on a bus, > > the set of all drivers for a bus, and > > the set of all children of a device, > > (not counting the set of all devices bound to a driver, since > there's already a patch to replace that with a mutex-protected > regular list) > > this limitation on adding or removing doesn't seem significant. There > aren't many places where these lists are iterated over or altered. We > could remove most of the overhead associated with klists and get rid of an > extra API for people to learn. > > Note that this would be very different from the old bus subsystem rwsem. > That protected too much -- everything associated with the bus subsystem -- > making it a pronounced chokepoint. My suggestion involves a separate > rwsem for each of these lists, so that none of them would be subject to > much contention.
Might also be worth to do a micro-benchmark for it (maybe in userland). The current klist code is far too complex for it's own good. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
