On Wed, 31 Jul 2019, Zebediah Figura wrote:
> On 7/31/19 7:06 AM, Peter Zijlstra wrote:
> > On Tue, Jul 30, 2019 at 06:06:02PM -0400, Gabriel Krisman Bertazi wrote:
> > > This is a new futex operation, called FUTEX_WAIT_MULTIPLE, which allows
> > > a thread to wait on several futexes at the same time, and be awoken by
> > > any of them. In a sense, it implements one of the features that was
> > > supported by pooling on the old FUTEX_FD interface.
> > >
> > > My use case for this operation lies in Wine, where we want to implement
> > > a similar interface available in Windows, used mainly for event
> > > handling. The wine folks have an implementation that uses eventfd, but
> > > it suffers from FD exhaustion (I was told they have application that go
> > > to the order of multi-milion FDs), and higher CPU utilization.
> >
> > So is multi-million the range we expect for @count ?
> >
>
> Not in Wine's case; in fact Wine has a hard limit of 64 synchronization
> primitives that can be waited on at once (which, with the current user-side
> code, translates into 65 futexes). The exhaustion just had to do with the
> number of primitives created; some programs seem to leak them badly.
And how is the futex approach better suited to 'fix' resource leaks?
Thanks,
tglx
