Kent Overstreet wrote:
> On Thu, Nov 29, 2012 at 09:54:47PM +0100, Andi Kleen wrote:
> > > > The regular atomic_t is limited in ways that you are not.
> > > > See my original mail.
> > >
> > > I don't follow, can you explain?
> >
> > For most cases the reference count is tied to some object, whic
On Thu, Nov 29, 2012 at 09:54:47PM +0100, Andi Kleen wrote:
> > > The regular atomic_t is limited in ways that you are not.
> > > See my original mail.
> >
> > I don't follow, can you explain?
>
> For most cases the reference count is tied to some object, which are
> naturally limited by memory s
> > The regular atomic_t is limited in ways that you are not.
> > See my original mail.
>
> I don't follow, can you explain?
For most cases the reference count is tied to some object, which are
naturally limited by memory size or other physical resources.
But in the assymetric CPU case with your
On Thu, Nov 29, 2012 at 12:42:17PM -0800, Andi Kleen wrote:
> Kent Overstreet writes:
>
> > On Thu, Nov 29, 2012 at 02:34:52PM -0500, Benjamin LaHaise wrote:
> >> On Thu, Nov 29, 2012 at 11:29:25AM -0800, Kent Overstreet wrote:
> >> > There's some kind of symmetry going on here, and if I'd been a
Kent Overstreet writes:
> On Thu, Nov 29, 2012 at 02:34:52PM -0500, Benjamin LaHaise wrote:
>> On Thu, Nov 29, 2012 at 11:29:25AM -0800, Kent Overstreet wrote:
>> > There's some kind of symmetry going on here, and if I'd been awake more
>> > in college I could probably say exactly why it works, b
On Thu, Nov 29, 2012 at 02:34:52PM -0500, Benjamin LaHaise wrote:
> On Thu, Nov 29, 2012 at 11:29:25AM -0800, Kent Overstreet wrote:
> > There's some kind of symmetry going on here, and if I'd been awake more
> > in college I could probably say exactly why it works, but it does.
>
> I think the ca
On Thu, Nov 29, 2012 at 11:29:25AM -0800, Kent Overstreet wrote:
> There's some kind of symmetry going on here, and if I'd been awake more
> in college I could probably say exactly why it works, but it does.
I think the catch is that using only a 32 bit counter is something the
user could arbitra
On Thu, Nov 29, 2012 at 08:20:03PM +0100, Andi Kleen wrote:
> > The trick is that we don't watch for the refcount hitting 0 until we're
> > shutting down - so this only works if you keep track of your initial
> > refcount. As long as we're not shutting down, we know the refcount can't
> > hit 0 bec
> The trick is that we don't watch for the refcount hitting 0 until we're
> shutting down - so this only works if you keep track of your initial
> refcount. As long as we're not shutting down, we know the refcount can't
> hit 0 because we haven't released the initial refcount.
This seems dangerous
On Thu, Nov 29, 2012 at 07:59:53PM +0100, Andi Kleen wrote:
> On Thu, Nov 29, 2012 at 10:57:20AM -0800, Kent Overstreet wrote:
> > On Thu, Nov 29, 2012 at 10:45:04AM -0800, Andi Kleen wrote:
> > > Kent Overstreet writes:
> > >
> > > > This implements a refcount with similar semantics to
> > > > a
On Thu, Nov 29, 2012 at 10:57:20AM -0800, Kent Overstreet wrote:
> On Thu, Nov 29, 2012 at 10:45:04AM -0800, Andi Kleen wrote:
> > Kent Overstreet writes:
> >
> > > This implements a refcount with similar semantics to
> > > atomic_get()/atomic_dec_and_test(), that starts out as just an atomic_t
>
On Thu, Nov 29, 2012 at 10:45:04AM -0800, Andi Kleen wrote:
> Kent Overstreet writes:
>
> > This implements a refcount with similar semantics to
> > atomic_get()/atomic_dec_and_test(), that starts out as just an atomic_t
> > but dynamically switches to per cpu refcounting when the rate of
> > get
Kent Overstreet writes:
> This implements a refcount with similar semantics to
> atomic_get()/atomic_dec_and_test(), that starts out as just an atomic_t
> but dynamically switches to per cpu refcounting when the rate of
> gets/puts becomes too high.
This will only work if you put on the same CPU
This implements a refcount with similar semantics to
atomic_get()/atomic_dec_and_test(), that starts out as just an atomic_t
but dynamically switches to per cpu refcounting when the rate of
gets/puts becomes too high.
It also implements two stage shutdown, as we need it to tear down the
percpu cou
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