Messages in this thread | | | Subject | Re: [Patch v2 2/3] iommu: optimize iova_magazine_free_pfns() | From | John Garry <> | Date | Fri, 29 Nov 2019 13:24:41 +0000 |
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On 29/11/2019 00:48, Cong Wang wrote: > If the maganize is empty, iova_magazine_free_pfns() should
magazine
> be a nop, however it misses the case of mag->size==0. So we > should just call iova_magazine_empty(). > > This should reduce the contention on iovad->iova_rbtree_lock > a little bit. > > Cc: Joerg Roedel <joro@8bytes.org> > Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> > --- > drivers/iommu/iova.c | 22 +++++++++++----------- > 1 file changed, 11 insertions(+), 11 deletions(-) > > diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c > index cb473ddce4cf..184d4c0e20b5 100644 > --- a/drivers/iommu/iova.c > +++ b/drivers/iommu/iova.c > @@ -797,13 +797,23 @@ static void iova_magazine_free(struct iova_magazine *mag) > kfree(mag); > } > > +static bool iova_magazine_full(struct iova_magazine *mag) > +{ > + return (mag && mag->size == IOVA_MAG_SIZE); > +} > + > +static bool iova_magazine_empty(struct iova_magazine *mag) > +{ > + return (!mag || mag->size == 0); > +} > + > static void > iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad) > { > unsigned long flags; > int i; > > - if (!mag) > + if (iova_magazine_empty(mag))
The only hot path we this call is __iova_rcache_insert()->iova_magazine_free_pfns(mag_to_free) and mag_to_free is full in this case, so I am sure how the additional check helps, right?
Thanks, John
> return; > > spin_lock_irqsave(&iovad->iova_rbtree_lock, flags); > @@ -820,16 +830,6 @@ iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad) > mag->size = 0; > } > > -static bool iova_magazine_full(struct iova_magazine *mag) > -{ > - return (mag && mag->size == IOVA_MAG_SIZE); > -} > - > -static bool iova_magazine_empty(struct iova_magazine *mag) > -{ > - return (!mag || mag->size == 0); > -} > - > static unsigned long iova_magazine_pop(struct iova_magazine *mag, > unsigned long limit_pfn) > { >
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