Re: [PATCH 05/12] net: mana: Set the DMA device max page size

Jason Gunthorpe
2022-05-17T19:35:32Z

On Tue, May 17, 2022 at 07:32:51PM +0000, Long Li wrote:
> > Subject: Re: [PATCH 05/12] net: mana: Set the DMA device max page size
> >
> > On Tue, May 17, 2022 at 02:04:29AM -0700, longli@linuxonhyperv.com wrote:
> > > From: Long Li <longli@microsoft.com>
> > >
> > > The system chooses default 64K page size if the device does not
> > > specify the max page size the device can handle for DMA. This do not
> > > work well when device is registering large chunk of memory in that a
> > > large page size is more efficient.
> > >
> > > Set it to the maximum hardware supported page size.
> >
> > For RDMA devices this should be set to the largest segment size an ib_sge can
> > take in when posting work. It should not be the page size of MR. 2M is a weird
> > number for that, are you sure it is right?
>
> Yes, this is the maximum page size used in hardware page tables.

As I said, it should be the size of the sge in the WQE, not the
"hardware page tables"

Jason