Re: [PATCH 18/23] vfs: Teach epoll to use file_hotplug_lock

Davide Libenzi
2009-06-03T15:03:56Z

On Tue, 2 Jun 2009, Eric W. Biederman wrote:

> I am not clear what problem you have.
>
> Is it the sprinkling the code that takes and removes the lock? Just
> the VFS needs to be involved with that. It is a slightly larger
> surface area than doing the work inside the file operations as we
> sometimes call the same method from 3-4 different places but it is
> definitely a bounded problem.
>
> Is it putting in the handful lines per subsystem to actually use this
> functionality? At that level something generic that is maintained
> outside of the subsystem is better than the mess we have with 4-5
> different implementations in the subsystems that need it, each having
> a different assortment of bugs.

Come on, only in the open fast path, there are at least two spin
lock/unlock and two atomic ops. Without even starting to count all the
extra branches and software added.
Is this stuff *really* needed, or we can faitly happily live w/out?

- Davide