On Tue, 2009-02-03 at 14:05 -0800, Andrew Morton wrote: > On Tue, 03 Feb 2009 22:55:26 +0100 > Eric Dumazet <dada1@xxxxxxxxxxxxx> wrote: > > > Andrew Morton a __crit : > > > On Mon, 2 Feb 2009 11:20:09 -0700 > > > Jonathan Corbet <corbet@xxxxxxx> wrote: > > > > > >> Matt Mackall suggested converting epoll's ep_lock to a bitlock as a way of > > >> saving space in struct file. This patch makes that change. > > > > > > hrm. bit_spin_lock() makes people upset (large penguiny people). iirc > > > it doesn't have all the correct/well-understood memory/compiler > > > ordering semantics which spinlocks have. And lockdep doesn't know about > > > it. > > > > > > > In a previous attempt (2005), I suggested using a single global lock. > > > > http://search.luky.org/linux-kernel.2005/msg50862.html > > ok.. > > > Probably an array of hashed spinlocks would be more than enough. > > > > yes, f_ep_lock is a teeny innermost lock. Perhaps using > f->f_dentry->d_inode->i_lock would be a decent speed/space compromise. That seems eminently reasonable. But that re-opens the question of what to do about poor Jon's quest. I got confused halfway through as he went from using a global fasync spinlock to a non-locked but atomic flag bit. Not sure why using a per-file or per-inode lock doesn't work for the fasync code. -- http://selenic.com : development and support for Mercurial and Linux -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
