Messages in this thread | | | From | Cong Wang <> | Date | Fri, 29 Nov 2019 22:02:08 -0800 | Subject | Re: [Patch v2 2/3] iommu: optimize iova_magazine_free_pfns() |
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On Fri, Nov 29, 2019 at 5:24 AM John Garry <john.garry@huawei.com> wrote: > > On 29/11/2019 00:48, Cong Wang wrote: > > If the maganize is empty, iova_magazine_free_pfns() should > > magazine
Good catch!
> > > 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?
This is what I mean by "a little bit" in changelog, did you miss it or misunderstand it? :)
Thanks.
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