RE: [PATCH V3,net-next] net: mana: Add page pool for RX buffers

[Haiyang Zhang]

> -----Original Message-----
> From: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> Sent: Monday, July 24, 2023 11:46 AM
> To: Jesper Dangaard Brouer <jbrouer@xxxxxxxxxx>; linux-
> hyperv@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx
> Cc: brouer@xxxxxxxxxx; Dexuan Cui <decui@xxxxxxxxxxxxx>; KY Srinivasan
> <kys@xxxxxxxxxxxxx>; Paul Rosswurm <paulros@xxxxxxxxxxxxx>;
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> wei.liu@xxxxxxxxxx; edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx;
> pabeni@xxxxxxxxxx; leon@xxxxxxxxxx; Long Li <longli@xxxxxxxxxxxxx>;
> ssengar@xxxxxxxxxxxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx;
> daniel@xxxxxxxxxxxxx; john.fastabend@xxxxxxxxx; bpf@xxxxxxxxxxxxxxx;
> ast@xxxxxxxxxx; Ajay Sharma <sharmaajay@xxxxxxxxxxxxx>; hawk@xxxxxxxxxx;
> tglx@xxxxxxxxxxxxx; shradhagupta@xxxxxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; Ilias Apalodimas <ilias.apalodimas@xxxxxxxxxx>; Jesper
> Dangaard Brouer <hawk@xxxxxxxxxx>
> Subject: RE: [PATCH V3,net-next] net: mana: Add page pool for RX buffers
> 
> 
> 
> > -----Original Message-----
> > From: Jesper Dangaard Brouer <jbrouer@xxxxxxxxxx>
> > Sent: Monday, July 24, 2023 7:29 AM
> > To: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; linux-hyperv@xxxxxxxxxxxxxxx;
> > netdev@xxxxxxxxxxxxxxx
> > Cc: brouer@xxxxxxxxxx; Dexuan Cui <decui@xxxxxxxxxxxxx>; KY Srinivasan
> > <kys@xxxxxxxxxxxxx>; Paul Rosswurm <paulros@xxxxxxxxxxxxx>;
> > olaf@xxxxxxxxx; vkuznets@xxxxxxxxxx; davem@xxxxxxxxxxxxx;
> > wei.liu@xxxxxxxxxx; edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx;
> > pabeni@xxxxxxxxxx; leon@xxxxxxxxxx; Long Li <longli@xxxxxxxxxxxxx>;
> > ssengar@xxxxxxxxxxxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx;
> > daniel@xxxxxxxxxxxxx; john.fastabend@xxxxxxxxx; bpf@xxxxxxxxxxxxxxx;
> > ast@xxxxxxxxxx; Ajay Sharma <sharmaajay@xxxxxxxxxxxxx>;
> hawk@xxxxxxxxxx;
> > tglx@xxxxxxxxxxxxx; shradhagupta@xxxxxxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; Ilias Apalodimas <ilias.apalodimas@xxxxxxxxxx>;
> Jesper
> > Dangaard Brouer <hawk@xxxxxxxxxx>
> > Subject: Re: [PATCH V3,net-next] net: mana: Add page pool for RX buffers
> >
> >
> >
> > On 21/07/2023 21.05, Haiyang Zhang wrote:
> > > Add page pool for RX buffers for faster buffer cycle and reduce CPU
> > > usage.
> > >
> > > The standard page pool API is used.
> > >
> > > Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> > > ---
> > > V3:
> > > Update xdp mem model, pool param, alloc as suggested by Jakub Kicinski
> > > V2:
> > > Use the standard page pool API as suggested by Jesper Dangaard Brouer
> > >
> > > ---
> > >   drivers/net/ethernet/microsoft/mana/mana_en.c | 91 +++++++++++++++--
> --
> > >   include/net/mana/mana.h                       |  3 +
> > >   2 files changed, 78 insertions(+), 16 deletions(-)
> > >
> > > diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c
> > b/drivers/net/ethernet/microsoft/mana/mana_en.c
> > > index a499e460594b..4307f25f8c7a 100644
> > > --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> > > +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> > [...]
> > > @@ -1659,6 +1679,8 @@ static void mana_poll_rx_cq(struct mana_cq *cq)
> > >
> > >   	if (rxq->xdp_flush)
> > >   		xdp_do_flush();
> > > +
> > > +	page_pool_nid_changed(rxq->page_pool, numa_mem_id());
> >
> > I don't think this page_pool_nid_changed() called is needed, if you do
> > as I suggest below (nid = NUMA_NO_NODE).
> >
> >
> > >   }
> > >
> > >   static int mana_cq_handler(void *context, struct gdma_queue
> > *gdma_queue)
> > [...]
> >
> > > @@ -2008,6 +2041,25 @@ static int mana_push_wqe(struct mana_rxq
> *rxq)
> > >   	return 0;
> > >   }
> > >
> > > +static int mana_create_page_pool(struct mana_rxq *rxq)
> > > +{
> > > +	struct page_pool_params pprm = {};
> >
> > You are implicitly assigning NUMA node id zero.
> >
> > > +	int ret;
> > > +
> > > +	pprm.pool_size = RX_BUFFERS_PER_QUEUE;
> > > +	pprm.napi = &rxq->rx_cq.napi;
> >
> > You likely want to assign pprm.nid to NUMA_NO_NODE
> >
> >   pprm.nid = NUMA_NO_NODE;
> >
> > For most drivers it is recommended to assign ``NUMA_NO_NODE`` (value -1)
> > as the NUMA ID to ``pp_params.nid``. When ``CONFIG_NUMA`` is enabled
> > this setting will automatically select the (preferred) NUMA node (via
> > ``numa_mem_id()``) based on where NAPI RX-processing is currently
> > running. The effect is that page_pool will only use recycled memory when
> > NUMA node match running CPU. This assumes CPU refilling driver RX-ring
> > will also run RX-NAPI.
> >
> > If a driver want more control over the NUMA node memory selection,
> > drivers can assign (``pp_params.nid``) something else than
> > `NUMA_NO_NODE`` and runtime adjust via function
> > ``page_pool_nid_changed()``.
> 
> Our driver is using NUMA 0 by default, so I implicitly assign NUMA node id
> to zero during pool init.
> 
> And, if the IRQ/CPU affinity is changed, the page_pool_nid_changed()
> will update the nid for the pool. Does this sound good?
> 

Also, since our driver is getting the default node from here:
	gc->numa_node = dev_to_node(&pdev->dev);
I will update this patch to set the default node as above, instead of implicitly
assigning it to 0.

Thanks,
- Haiyang