[dpdk-stable] [dpdk-dev] [PATCH v8 1/3] vfio: revert changes for map contiguous areas in one go

Nithin Dabilpuram nithind1988 at gmail.com
Fri Mar 5 16:50:16 CET 2021


On Fri, Mar 05, 2021 at 01:54:34PM +0000, Burakov, Anatoly wrote:
> On 05-Mar-21 7:50 AM, David Marchand wrote:
> > On Fri, Jan 15, 2021 at 8:33 AM Nithin Dabilpuram
> > <ndabilpuram at marvell.com> wrote:
> > > 
> > > In order to save DMA entries limited by kernel both for externel
> > > memory and hugepage memory, an attempt was made to map physically
> > > contiguous memory in one go. This cannot be done as VFIO IOMMU type1
> > > does not support partially unmapping a previously mapped memory
> > > region while Heap can request for multi page mapping and
> > > partial unmapping.
> > > Hence for going back to old method of mapping/unmapping at
> > > memseg granularity, this commit reverts
> > > commit d1c7c0cdf7ba ("vfio: map contiguous areas in one go")
> > > 
> > > Also add documentation on what module parameter needs to be used
> > > to increase the per-container dma map limit for VFIO.
> > > 
> > > Fixes: d1c7c0cdf7ba ("vfio: map contiguous areas in one go")
> > > Cc: anatoly.burakov at intel.com
> > > Cc: stable at dpdk.org
> > > 
> > > Signed-off-by: Nithin Dabilpuram <ndabilpuram at marvell.com>
> > > Acked-by: Anatoly Burakov <anatoly.burakov at intel.com>
> > > Acked-by: David Christensen <drc at linux.vnet.ibm.com>
> > 
> > There is a regression reported in bz: https://bugs.dpdk.org/show_bug.cgi?id=649
> > 
> > I assigned it to Anatoly for now.
> > Nithin, can you have a loo too?
> > 
> > Thanks.
> > 
> > 
> 
> I've responded on the bug tracker as well, but to repeat it here: this is
> not a regression, this is intended behavior. We cannot do anything about
> this.

To add, for test case to pass, either limits have to be increased, or use "--mp-alloc=xmemhuge" 
instead of "--mp-alloc=xmem" which is forcing system page size or reduce total mbuf count
to reduce page count.

> 
> -- 
> Thanks,
> Anatoly


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