From: Lorenzo Bianconi <lorenzo@kernel.org>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, davem@davemloft.net,
lorenzo.bianconi@redhat.com, echaudro@redhat.com,
sameehj@amazon.com, kuba@kernel.org, john.fastabend@gmail.com,
daniel@iogearbox.net, ast@kernel.org, shayagr@amazon.com,
intel-wired-lan <intel-wired-lan@lists.osuosl.org>
Subject: Re: [PATCH v2 net-next 2/9] xdp: initialize xdp_buff mb bit to 0 in all XDP drivers
Date: Fri, 4 Sep 2020 09:54:41 +0200 [thread overview]
Message-ID: <20200904075441.GD2884@lore-desk> (raw)
In-Reply-To: <20200904093542.4dc43682@carbon>
[-- Attachment #1: Type: text/plain, Size: 1284 bytes --]
> On Thu, 3 Sep 2020 22:58:46 +0200
> Lorenzo Bianconi <lorenzo@kernel.org> wrote:
>
> > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> > index 0b675c34ce49..20c8fd3cd4a3 100644
> > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> > @@ -2298,6 +2298,7 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
> > #if (PAGE_SIZE < 8192)
> > xdp.frame_sz = ixgbe_rx_frame_truesize(rx_ring, 0);
> > #endif
> > + xdp.mb = 0;
> >
> > while (likely(total_rx_packets < budget)) {
> > union ixgbe_adv_rx_desc *rx_desc;
>
> In this ixgbe driver you are smart and init the xdp.mb bit outside the
> (like xdp.frame_sz, when frame_sz is constant). This is a nice
> optimization, but the driver developer that adds XDP multi-buffer
> support must remember to reset it. The patch itself is okay, it is
> just something to keep in-mind when reviewing/changing drivers.
yes, I have just decided to avoid unnecessary instructions for the moment.
Regards,
Lorenzo
>
> --
> Best regards,
> Jesper Dangaard Brouer
> MSc.CS, Principal Kernel Engineer at Red Hat
> LinkedIn: http://www.linkedin.com/in/brouer
>
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WARNING: multiple messages have this Message-ID (diff)
From: Lorenzo Bianconi <lorenzo@kernel.org>
To: intel-wired-lan@osuosl.org
Subject: [Intel-wired-lan] [PATCH v2 net-next 2/9] xdp: initialize xdp_buff mb bit to 0 in all XDP drivers
Date: Fri, 4 Sep 2020 09:54:41 +0200 [thread overview]
Message-ID: <20200904075441.GD2884@lore-desk> (raw)
In-Reply-To: <20200904093542.4dc43682@carbon>
> On Thu, 3 Sep 2020 22:58:46 +0200
> Lorenzo Bianconi <lorenzo@kernel.org> wrote:
>
> > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> > index 0b675c34ce49..20c8fd3cd4a3 100644
> > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> > @@ -2298,6 +2298,7 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
> > #if (PAGE_SIZE < 8192)
> > xdp.frame_sz = ixgbe_rx_frame_truesize(rx_ring, 0);
> > #endif
> > + xdp.mb = 0;
> >
> > while (likely(total_rx_packets < budget)) {
> > union ixgbe_adv_rx_desc *rx_desc;
>
> In this ixgbe driver you are smart and init the xdp.mb bit outside the
> (like xdp.frame_sz, when frame_sz is constant). This is a nice
> optimization, but the driver developer that adds XDP multi-buffer
> support must remember to reset it. The patch itself is okay, it is
> just something to keep in-mind when reviewing/changing drivers.
yes, I have just decided to avoid unnecessary instructions for the moment.
Regards,
Lorenzo
>
> --
> Best regards,
> Jesper Dangaard Brouer
> MSc.CS, Principal Kernel Engineer at Red Hat
> LinkedIn: http://www.linkedin.com/in/brouer
>
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next prev parent reply other threads:[~2020-09-04 7:54 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-03 20:58 [PATCH v2 net-next 0/9] mvneta: introduce XDP multi-buffer support Lorenzo Bianconi
2020-09-03 20:58 ` [PATCH v2 net-next 1/9] xdp: introduce mb in xdp_buff/xdp_frame Lorenzo Bianconi
2020-09-04 1:07 ` Alexei Starovoitov
2020-09-04 7:19 ` Jesper Dangaard Brouer
2020-09-04 15:15 ` David Ahern
2020-09-04 15:59 ` Jesper Dangaard Brouer
2020-09-04 16:30 ` David Ahern
2020-09-07 18:02 ` Jesper Dangaard Brouer
2020-09-08 1:22 ` David Ahern
2020-09-03 20:58 ` [PATCH v2 net-next 2/9] xdp: initialize xdp_buff mb bit to 0 in all XDP drivers Lorenzo Bianconi
2020-09-04 7:35 ` Jesper Dangaard Brouer
2020-09-04 7:35 ` [Intel-wired-lan] " Jesper Dangaard Brouer
2020-09-04 7:54 ` Lorenzo Bianconi [this message]
2020-09-04 7:54 ` Lorenzo Bianconi
2020-09-03 20:58 ` [PATCH v2 net-next 3/9] net: mvneta: update mb bit before passing the xdp buffer to eBPF layer Lorenzo Bianconi
2020-09-06 7:33 ` Shay Agroskin
2020-09-06 9:05 ` Lorenzo Bianconi
2020-09-03 20:58 ` [PATCH v2 net-next 4/9] xdp: add multi-buff support to xdp_return_{buff/frame} Lorenzo Bianconi
2020-09-03 20:58 ` [PATCH v2 net-next 5/9] net: mvneta: add multi buffer support to XDP_TX Lorenzo Bianconi
2020-09-06 7:20 ` Shay Agroskin
2020-09-06 8:43 ` Lorenzo Bianconi
2020-09-03 20:58 ` [PATCH v2 net-next 6/9] bpf: helpers: add bpf_xdp_adjust_mb_header helper Lorenzo Bianconi
2020-09-04 1:09 ` Alexei Starovoitov
2020-09-04 8:07 ` Lorenzo Bianconi
2020-09-04 1:13 ` Alexei Starovoitov
2020-09-04 7:50 ` Lorenzo Bianconi
2020-09-04 13:52 ` Jesper Dangaard Brouer
2020-09-04 14:27 ` Lorenzo Bianconi
2020-09-04 6:47 ` John Fastabend
2020-09-04 9:45 ` Lorenzo Bianconi
2020-09-04 15:23 ` John Fastabend
2020-09-06 13:36 ` Lorenzo Bianconi
2020-09-08 19:57 ` John Fastabend
2020-09-08 21:31 ` Lorenzo Bianconi
2020-09-09 20:51 ` Lorenzo Bianconi
2020-09-03 20:58 ` [PATCH v2 net-next 7/9] bpf: helpers: add multibuffer support Lorenzo Bianconi
2020-09-03 21:24 ` Maciej Fijalkowski
2020-09-04 9:47 ` Lorenzo Bianconi
2020-09-03 20:58 ` [PATCH v2 net-next 8/9] samples/bpf: add bpf program that uses xdp mb helpers Lorenzo Bianconi
2020-09-03 20:58 ` [PATCH v2 net-next 9/9] net: mvneta: enable jumbo frames for XDP Lorenzo Bianconi
2020-09-04 1:08 ` [PATCH v2 net-next 0/9] mvneta: introduce XDP multi-buffer support Alexei Starovoitov
2020-09-04 7:40 ` Lorenzo Bianconi
2020-09-04 5:41 ` John Fastabend
2020-09-04 7:39 ` Lorenzo Bianconi
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