Re: Re: [PATCH net-next v3] octeontx2-pf: Add support for page pool

[Simon Horman]

On Fri, May 19, 2023 at 10:21:44AM +0000, Ratheesh Kannoth wrote:
> 
> > -----Original Message-----
> > From: Simon Horman <simon.horman@xxxxxxxxxxxx>
> > Sent: Friday, May 19, 2023 3:33 PM
> > To: Ratheesh Kannoth <rkannoth@xxxxxxxxxxx>
> > Cc: netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Sunil Kovvuri
> > Goutham <sgoutham@xxxxxxxxxxx>; davem@xxxxxxxxxxxxx;
> > edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx;
> > linyunsheng@xxxxxxxxxx; Subbaraya Sundeep Bhatta
> > <sbhatta@xxxxxxxxxxx>; Geethasowjanya Akula <gakula@xxxxxxxxxxx>;
> > Srujana Challa <schalla@xxxxxxxxxxx>; Hariprasad Kelam
> > <hkelam@xxxxxxxxxxx>
> > Subject: [EXT] Re: [PATCH net-next v3] octeontx2-pf: Add support for page
> > pool
> > 
> > External Email
> > 
> > ----------------------------------------------------------------------
> > On Fri, May 19, 2023 at 12:43:52PM +0530, Ratheesh Kannoth wrote:
> > > Page pool for each rx queue enhance rx side performance by reclaiming
> > > buffers back to each queue specific pool. DMA mapping is done only for
> > > first allocation of buffers.
> > > As subsequent buffers allocation avoid DMA mapping, it results in
> > > performance improvement.
> > >
> > > Image        |  Performance
> > > ------------ | ------------
> > > Vannila      |   3Mpps
> > >              |
> > > with this    |   42Mpps
> > > change	     |
> > > ---------------------------
> > >
> > > Signed-off-by: Ratheesh Kannoth <rkannoth@xxxxxxxxxxx>
> > 
> > ...
> > 
> > > @@ -1205,10 +1226,28 @@ void otx2_sq_free_sqbs(struct otx2_nic *pfvf)
> > >  	}
> > >  }
> > >
> > > +void otx2_free_bufs(struct otx2_nic *pfvf, struct otx2_pool *pool,
> > > +		    u64 iova, int size)
> > > +{
> > > +	u64 pa = otx2_iova_to_phys(pfvf->iommu_domain, iova);
> > > +	struct page *page = virt_to_head_page(phys_to_virt(pa));
> > 
> > nit: please arrange local variables in networking code in reverse xmas tree
> >      order - longest line to shortest.
> Variable "pa" is used in second line.  Are you suggesting to defer assignment later; and only declare variables here in reverse xmas tree style ? 

Yes, that is my suggestion.