From: Kent Overstreet
Percpu frontend for allocating ids. With percpu allocation (that works),
it's impossible to guarantee it will always be possible to allocate all
nr_tags - typically, some will be stuck on a remote percpu freelist
where the current job can't get to them.
We do guarantee that
On Tue, Aug 20, 2013 at 02:31:57PM -0700, Andrew Morton wrote:
> On Fri, 16 Aug 2013 23:09:06 + "Nicholas A. Bellinger"
> wrote:
>
> > From: Kent Overstreet
> >
> > Percpu frontend for allocating ids. With percpu allocation (that works),
> > it's impossible to guarantee it will always be p
On Wed, Aug 21, 2013 at 06:25:58PM +, Christoph Lameter wrote:
> On Fri, 16 Aug 2013, Nicholas A. Bellinger wrote:
>
> > + spinlock_t lock;
>
> Remove the spinlock.
As Andrew noted, the spinlock is needed because of tag stealing. (You
don't think I'd stick a spinlock o
On Tue, Aug 20, 2013 at 02:31:57PM -0700, Andrew Morton wrote:
> On Fri, 16 Aug 2013 23:09:06 + "Nicholas A. Bellinger"
> wrote:
> > + /*
> > +* Bitmap of cpus that (may) have tags on their percpu freelists:
> > +* steal_tags() uses this to decide when to steal tags, and which cpus
On Wed, 28 Aug 2013 12:53:17 -0700 Kent Overstreet wrote:
> > > + while (1) {
> > > + spin_lock(&pool->lock);
> > > +
> > > + /*
> > > + * prepare_to_wait() must come before steal_tags(), in case
> > > + * percpu_ida_free() on another cpu flips a bit in
> > > +
On Wed, Aug 28, 2013 at 01:23:32PM -0700, Andrew Morton wrote:
> On Wed, 28 Aug 2013 12:53:17 -0700 Kent Overstreet wrote:
>
> > > > + while (1) {
> > > > + spin_lock(&pool->lock);
> > > > +
> > > > + /*
> > > > +* prepare_to_wait() must come befo
On Wed, 28 Aug 2013 13:44:54 -0700 Kent Overstreet wrote:
> > > > What guarantees that this wait will terminate?
> > >
> > > It seems fairly clear to me from the break statement a couple lines up;
> > > if we were passed __GFP_WAIT we terminate iff we succesfully allocated a
> > > tag. If we wer
On Wed, Aug 28, 2013 at 01:50:42PM -0700, Andrew Morton wrote:
> On Wed, 28 Aug 2013 13:44:54 -0700 Kent Overstreet wrote:
>
> > > > > What guarantees that this wait will terminate?
> > > >
> > > > It seems fairly clear to me from the break statement a couple lines up;
> > > > if we were passed
On Wed, 28 Aug 2013 14:12:17 -0700 Kent Overstreet wrote:
> How's this look?
>
> diff --git a/lib/idr.c b/lib/idr.c
> index 15c021c..a3f8e9a 100644
> --- a/lib/idr.c
> +++ b/lib/idr.c
> @@ -1288,6 +1288,11 @@ static inline unsigned alloc_local_tag(struct
> percpu_ida *pool,
> * Safe to be cal
On Fri, 16 Aug 2013 23:09:06 + "Nicholas A. Bellinger"
wrote:
> From: Kent Overstreet
>
> Percpu frontend for allocating ids. With percpu allocation (that works),
> it's impossible to guarantee it will always be possible to allocate all
> nr_tags - typically, some will be stuck on a remote
On Fri, 16 Aug 2013, Nicholas A. Bellinger wrote:
> + spinlock_t lock;
Remove the spinlock.
> + unsignednr_free;
> + unsignedfreelist[];
> +};
> +
> +static inline void move_tags(unsigned *dst, unsigned *dst_nr,
> +
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