Re: [PATCH v2 5/8] iommu/io-pgtable-arm: Support lockless operation

Linu Cherian
2017-06-27T09:08:24Z

On Tue Jun 27, 2017 at 09:39:13AM +0100, Will Deacon wrote:
> On Tue, Jun 27, 2017 at 10:41:55AM +0530, Linu Cherian wrote:
> > On Fri Jun 23, 2017 at 05:04:05PM +0530, Linu Cherian wrote:
> > > On Fri Jun 23, 2017 at 11:35:25AM +0100, Robin Murphy wrote:
> > > > Note that on a coherent platform like ThunderX that's as good as just
> > > > deleting it, because you'll never execute the case below. However, on
> > > > reflection I think it can at least safely be downgraded to dma_wmb()
> > > > (i.e. DMB) rather than a full DSB - would you be able to test what
> > > > difference that makes?
> > >
> > > The testing was done on Thunderx 1, which has a non coherent page table walk.
> > > Yes, downgrading to dma_wmb() helps. With this change, performance is back to v1.
> > >
> >
> > Should i send a patch for this ?
>
> I already did it:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/commit/?h=for-joerg/arm-smmu/updates&id=77f3445866c39d8866b31d8d9fa47c7c20938e05
>
> Will
>
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Thanks Will.

--
Linu cherian