linux-kernel - RE: [PATCH] net: mana: Batch ringing RX queue doorbell on receiving packets

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Date:   Fri, 16 Jun 2023 18:54:33 +0000
From:   Long Li <longli@...rosoft.com>
To:     Haiyang Zhang <haiyangz@...rosoft.com>,
        "longli@...uxonhyperv.com" <longli@...uxonhyperv.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Leon Romanovsky <leon@...nel.org>,
        Shradha Gupta <shradhagupta@...ux.microsoft.com>,
        Ajay Sharma <sharmaajay@...rosoft.com>,
        Shachar Raindel <shacharr@...rosoft.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: RE: [PATCH] net: mana: Batch ringing RX queue doorbell on receiving
 packets

Hi,

I'm sending v2 to address some corner cases discovered during tests.

Thanks,
Long

> -----Original Message-----
> From: Haiyang Zhang <haiyangz@...rosoft.com>
> Sent: Friday, June 16, 2023 9:49 AM
> To: longli@...uxonhyperv.com; KY Srinivasan <kys@...rosoft.com>; Wei Liu
> <wei.liu@...nel.org>; Dexuan Cui <decui@...rosoft.com>; David S. Miller
> <davem@...emloft.net>; Eric Dumazet <edumazet@...gle.com>; Jakub
> Kicinski <kuba@...nel.org>; Paolo Abeni <pabeni@...hat.com>; Leon
> Romanovsky <leon@...nel.org>; Shradha Gupta
> <shradhagupta@...ux.microsoft.com>; Ajay Sharma
> <sharmaajay@...rosoft.com>; Shachar Raindel <shacharr@...rosoft.com>;
> Stephen Hemminger <stephen@...workplumber.org>; linux-
> hyperv@...r.kernel.org; netdev@...r.kernel.org; linux-
> kernel@...r.kernel.org
> Cc: linux-rdma@...r.kernel.org; Long Li <longli@...rosoft.com>;
> stable@...r.kernel.org
> Subject: RE: [PATCH] net: mana: Batch ringing RX queue doorbell on receiving
> packets
> 
> 
> 
> > -----Original Message-----
> > From: longli@...uxonhyperv.com <longli@...uxonhyperv.com>
> > Sent: Thursday, June 15, 2023 7:28 PM
> > To: KY Srinivasan <kys@...rosoft.com>; Haiyang Zhang
> > <haiyangz@...rosoft.com>; Wei Liu <wei.liu@...nel.org>; Dexuan Cui
> > <decui@...rosoft.com>; David S. Miller <davem@...emloft.net>; Eric
> > Dumazet <edumazet@...gle.com>; Jakub Kicinski <kuba@...nel.org>;
> Paolo
> > Abeni <pabeni@...hat.com>; Leon Romanovsky <leon@...nel.org>;
> Shradha
> > Gupta <shradhagupta@...ux.microsoft.com>; Ajay Sharma
> > <sharmaajay@...rosoft.com>; Shachar Raindel <shacharr@...rosoft.com>;
> > Stephen Hemminger <stephen@...workplumber.org>; linux-
> > hyperv@...r.kernel.org; netdev@...r.kernel.org; linux-
> > kernel@...r.kernel.org
> > Cc: linux-rdma@...r.kernel.org; Long Li <longli@...rosoft.com>;
> > stable@...r.kernel.org
> > Subject: [PATCH] net: mana: Batch ringing RX queue doorbell on
> > receiving packets
> >
> > From: Long Li <longli@...rosoft.com>
> >
> > It's inefficient to ring the doorbell page every time a WQE is posted
> > to the received queue.
> >
> > Move the code for ringing doorbell page to where after we have posted
> > all WQEs to the receive queue during a callback from napi_poll().
> >
> > Tests showed no regression in network latency benchmarks.
> >
> > Cc: stable@...r.kernel.org
> > Fixes: ca9c54d2d6a5 ("net: mana: Add a driver for Microsoft Azure
> > Network Adapter (MANA)")
> > Signed-off-by: Long Li <longli@...rosoft.com>
> > ---
> >  drivers/net/ethernet/microsoft/mana/mana_en.c | 10 ++++++++--
> >  1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c
> > b/drivers/net/ethernet/microsoft/mana/mana_en.c
> > index cd4d5ceb9f2d..ef1f0ce8e44d 100644
> > --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> > +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> > @@ -1383,8 +1383,8 @@ static void mana_post_pkt_rxq(struct mana_rxq
> > *rxq)
> >
> >  	recv_buf_oob = &rxq->rx_oobs[curr_index];
> >
> > -	err = mana_gd_post_and_ring(rxq->gdma_rq, &recv_buf_oob-
> > >wqe_req,
> > -				    &recv_buf_oob->wqe_inf);
> > +	err = mana_gd_post_work_request(rxq->gdma_rq, &recv_buf_oob-
> > >wqe_req,
> > +					&recv_buf_oob->wqe_inf);
> >  	if (WARN_ON_ONCE(err))
> >  		return;
> >
> > @@ -1654,6 +1654,12 @@ static void mana_poll_rx_cq(struct mana_cq
> *cq)
> >  		mana_process_rx_cqe(rxq, cq, &comp[i]);
> >  	}
> >
> > +	if (comp_read) {
> > +		struct gdma_context *gc = rxq->gdma_rq->gdma_dev-
> > >gdma_context;
> > +
> > +		mana_gd_wq_ring_doorbell(gc, rxq->gdma_rq);
> > +	}
> > +
> 
> Thank you!
> 
> Reviewed-by: Haiyang Zhang <haiyangz@...rosoft.com>