Re: [PATCH 04/23] vfs: Introduce infrastructure for revoking a file

Nick Piggin
2009-06-03T06:38:23Z

On Tue, Jun 02, 2009 at 03:56:02PM -0700, Eric W. Biederman wrote:
> Nick Piggin <npiggin@suse.de> writes:
>
> >> In addition for a complete solution we need:
> >> - A reliable way the file structures that we need to revoke.
> >> - To wait for but not tamper with ongoing file creation and cleanup.
> >> - A guarantee that all with user space controlled duration are removed.
> >>
> >> The file_hotplug_lock has a very unique implementation necessitated by
> >> the need to have no performance impact on existing code. Classic locking
> >
> > Well, it isn't no performance impact. Function calls, branches, icache
> > and dcache...
>
> Practically none.

OK that's different from none. There is obviously overhead.