Messages in this thread | | | Date | Mon, 30 Mar 2009 17:19:45 -0400 (EDT) | From | Christoph Lameter <> | Subject | Re: [patch 1/3] slub: add per-cache slab thrash ratio |
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On Mon, 30 Mar 2009, David Rientjes wrote:
> > > + if (oo_objects(s->oo)) > > > + thrash_ratio = s->min_free_watermark * 100 / oo_objects(s->oo); > > > s->oo = oo_make(order, size); > > > > s->oo is set *after* you check it. Check oo_objects after the value has > > been set please. > > > > It's actually right the way I implemented it, oo_objects(s->oo) will be 0 > when this is called for kmem_cache_open() meaning there is no preexisting > slab_thrash_ratio. But this check is required when calculate_sizes() is > called from order_store() to adjust the slab_thrash_ratio for the new > objects per slab. The above check is saving the old thrash ratio so > the new s->min_free_watermark value can be set following the > oo_make(). This was mentioned in the changelog for this patch: > > The value is stored in terms of the number of objects that the > ratio represents, not the ratio itself. This avoids costly > arithmetic in the slowpath for a calculation that could otherwise > be done only when `slab_thrash_ratio' or `order' is changed.
Then its the wrong place to set it. Initializations are done in kmem_cache_open() after calculate_sizes are called.
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