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From: Magnus Karlsson <magnus.karlsson@gmail.com>
To: Martin Lau <kafai@fb.com>
Cc: Magnus Karlsson <magnus.karlsson@intel.com>,
	"bjorn.topel@intel.com" <bjorn.topel@intel.com>,
	"ast@kernel.org" <ast@kernel.org>,
	"daniel@iogearbox.net" <daniel@iogearbox.net>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"jonathan.lemon@gmail.com" <jonathan.lemon@gmail.com>,
	"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	"saeedm@mellanox.com" <saeedm@mellanox.com>,
	"jeffrey.t.kirsher@intel.com" <jeffrey.t.kirsher@intel.com>,
	"maciej.fijalkowski@intel.com" <maciej.fijalkowski@intel.com>,
	"maciejromanfijalkowski@gmail.com"
	<maciejromanfijalkowski@gmail.com>
Subject: Re: [PATCH bpf-next 02/12] xsk: consolidate to one single cached producer pointer
Date: Tue, 10 Dec 2019 10:04:58 +0100	[thread overview]
Message-ID: <CAJ8uoz3o23wbezwLpONts=qTdC1Fr9JK1hD=fkwF4snS2Jdqbg@mail.gmail.com> (raw)
In-Reply-To: <20191210004254.m5cicj3tkc2bhlrd@kafai-mbp>

On Tue, Dec 10, 2019 at 1:43 AM Martin Lau <kafai@fb.com> wrote:
>
> On Mon, Dec 09, 2019 at 08:56:19AM +0100, Magnus Karlsson wrote:
> > Currently, the xsk ring code has two cached producer pointers:
> > prod_head and prod_tail. This patch consolidates these two into a
> > single one called cached_prod to make the code simpler and easier to
> > maintain. This will be in line with the user space part of the the
> > code found in libbpf, that only uses a single cached pointer.
> >
> > The Rx path only uses the two top level functions
> > xskq_produce_batch_desc and xskq_produce_flush_desc and they both use
> > prod_head and never prod_tail. So just move them over to
> > cached_prod.
> >
> > The Tx XDP_DRV path uses xskq_produce_addr_lazy and
> > xskq_produce_flush_addr_n and unnecessarily operates on both prod_tail
> > and prod_cons, so move them over to just use cached_prod by skipping
> prod_cons or prod_head?

Thanks. It should read prod_head. Will fix in a v2.

/Magnus

> > the intermediate step of updating prod_tail.
> >
> > The Tx path in XDP_SKB mode uses xskq_reserve_addr and
> > xskq_produce_addr. They currently use both cached pointers, but we can
> > operate on the global producer pointer in xskq_produce_addr since it
> > has to be updated anyway, thus eliminating the use of both cached
> > pointers. We can also remove the xskq_nb_free in xskq_produce_addr
> > since it is already called in xskq_reserve_addr. No need to do it
> > twice.
> >
> > When there is only one cached producer pointer, we can also simplify
> > xskq_nb_free by removing one argument.

  reply	other threads:[~2019-12-10  9:05 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-09  7:56 [PATCH bpf-next 00/12] xsk: clean up ring access functions Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 01/12] xsk: eliminate the lazy update threshold Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 02/12] xsk: consolidate to one single cached producer pointer Magnus Karlsson
2019-12-10  0:42   ` Martin Lau
2019-12-10  9:04     ` Magnus Karlsson [this message]
2019-12-13 18:04   ` Maxim Mikityanskiy
2019-12-16  8:46     ` Magnus Karlsson
2019-12-19 14:35       ` Maxim Mikityanskiy
2019-12-19 16:21         ` Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 03/12] xsk: standardize naming of producer ring access functions Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 04/12] xsk: simplify detection of empty and full rings Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 05/12] xsk: eliminate the RX batch size Magnus Karlsson
2019-12-09 10:16   ` Sergei Shtylyov
2019-12-09 13:07     ` Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 06/12] xsk: simplify xskq_nb_avail and xskq_nb_free Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 07/12] xsk: simplify the consumer ring access functions Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 08/12] xsk: change names of validation functions Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 09/12] xsk: ixgbe: i40e: ice: mlx5: xsk_umem_discard_addr to xsk_umem_release_addr Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 10/12] xsk: remove unnecessary READ_ONCE of data Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 11/12] xsk: add function naming comments and reorder functions Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 12/12] xsk: use struct_size() helper Magnus Karlsson
2019-12-10  1:02 ` [PATCH bpf-next 00/12] xsk: clean up ring access functions Martin Lau

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