Messages in this thread Patch in this message | | | Date | Tue, 31 May 2022 20:48:24 +0100 | Subject | Re: [PATCH 04/10] dmapool: improve accuracy of debug statistics | From | Robin Murphy <> |
| |
On 2022-05-31 19:17, Tony Battersby wrote: > The "total number of blocks in pool" debug statistic currently does not > take the boundary value into account, so it diverges from the "total > number of blocks in use" statistic when a boundary is in effect. Add a > calculation for the number of blocks per allocation that takes the > boundary into account, and use it to replace the inaccurate calculation. > > This depends on the patch "dmapool: fix boundary comparison" for the > calculated blks_per_alloc value to be correct. > > Signed-off-by: Tony Battersby <tonyb@cybernetics.com> > --- > mm/dmapool.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/mm/dmapool.c b/mm/dmapool.c > index 782143144a32..9e30f4425dea 100644 > --- a/mm/dmapool.c > +++ b/mm/dmapool.c > @@ -47,6 +47,7 @@ struct dma_pool { /* the pool */ > struct device *dev; > unsigned int allocation; > unsigned int boundary; > + unsigned int blks_per_alloc; > char name[32]; > struct list_head pools; > }; > @@ -92,8 +93,7 @@ static ssize_t pools_show(struct device *dev, struct device_attribute *attr, cha > /* per-pool info, no real statistics yet */ > temp = scnprintf(next, size, "%-16s %4zu %4zu %4u %2u\n",
Nit: if we're tinkering with this, it's probably worth updating the whole function to use sysfs_emit{_at}().
> pool->name, blocks, > - (size_t) pages * > - (pool->allocation / pool->size), > + (size_t) pages * pool->blks_per_alloc, > pool->size, pages); > size -= temp; > next += temp; > @@ -168,6 +168,9 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev, > retval->size = size; > retval->boundary = boundary; > retval->allocation = allocation; > + retval->blks_per_alloc = > + (allocation / boundary) * (boundary / size) + > + (allocation % boundary) / size;
Do we really need to store this? Sure, 4 divisions (which could possibly be fewer given the constraints on boundary) isn't the absolute cheapest calculation, but I still can't imagine anyone would be polling sysfs stats hard enough to even notice.
Thanks, Robin.
> > INIT_LIST_HEAD(&retval->pools); >
| |