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From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: "John Fastabend" <john.fastabend@gmail.com>,
	"Björn Töpel" <bjorn.topel@gmail.com>,
	"John Fastabend" <john.fastabend@gmail.com>
Cc: Netdev <netdev@vger.kernel.org>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Björn Töpel" <bjorn.topel@intel.com>, bpf <bpf@vger.kernel.org>,
	"David Miller" <davem@davemloft.net>,
	"Jakub Kicinski" <jakub.kicinski@netronome.com>,
	"Jesper Dangaard Brouer" <hawk@kernel.org>,
	"Karlsson, Magnus" <magnus.karlsson@intel.com>,
	"Jonathan Lemon" <jonathan.lemon@gmail.com>
Subject: Re: [PATCH bpf-next v2 4/8] xsk: make xskmap flush_list common for all map instances
Date: Wed, 08 Jan 2020 17:01:08 +0100	[thread overview]
Message-ID: <87lfqigcor.fsf@toke.dk> (raw)
In-Reply-To: <5e15faaac42e7_67ea2afd262665bc44@john-XPS-13-9370.notmuch>

John Fastabend <john.fastabend@gmail.com> writes:

> Björn Töpel wrote:
>> On Tue, 7 Jan 2020 at 18:54, John Fastabend <john.fastabend@gmail.com> wrote:
>> >
>> > Björn Töpel wrote:
>> > > From: Björn Töpel <bjorn.topel@intel.com>
>> > >
>> > > The xskmap flush list is used to track entries that need to flushed
>> > > from via the xdp_do_flush_map() function. This list used to be
>> > > per-map, but there is really no reason for that. Instead make the
>> > > flush list global for all xskmaps, which simplifies __xsk_map_flush()
>> > > and xsk_map_alloc().
>> > >
>> > > Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
>> > > Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
>> > > ---
>> >
>> > Just to check. The reason this is OK is because xdp_do_flush_map()
>> > is called from NAPI context and is per CPU so the only entries on
>> > the list will be from the current cpu napi context?
>> 
>> Correct!
>> 
>> > Even in the case
>> > where multiple xskmaps exist we can't have entries from more than
>> > a single map on any list at the same time by my reading.
>> >
>> 
>> No, there can be entries from different (XSK) maps. Instead of
>> focusing on maps to flush, focus on *entries* to flush. At the end of
>> the poll function, all entries (regardless of map origin) will be
>> flushed. Makes sense?
>
> Ah OK. This would mean that a single program used multiple maps
> though correct? Because we can only run a single BPF program per
> NAPI context.

Yeah, there's nothing limiting each program to a single map (of any
type)...

-Toke


  reply	other threads:[~2020-01-08 16:01 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-19  6:09 [PATCH bpf-next v2 0/8] Simplify xdp_do_redirect_map()/xdp_do_flush_map() and XDP maps Björn Töpel
2019-12-19  6:09 ` [PATCH bpf-next v2 1/8] xdp: simplify devmap cleanup Björn Töpel
2020-01-07 17:32   ` John Fastabend
2020-01-08 10:08     ` Björn Töpel
2019-12-19  6:10 ` [PATCH bpf-next v2 2/8] xdp: simplify cpumap cleanup Björn Töpel
2019-12-19  6:10 ` [PATCH bpf-next v2 3/8] xdp: fix graze->grace type-o in cpumap comments Björn Töpel
2020-01-07 17:33   ` John Fastabend
2019-12-19  6:10 ` [PATCH bpf-next v2 4/8] xsk: make xskmap flush_list common for all map instances Björn Töpel
2020-01-07 17:54   ` John Fastabend
2020-01-08 10:13     ` Björn Töpel
2020-01-08 15:52       ` John Fastabend
2020-01-08 16:01         ` Toke Høiland-Jørgensen [this message]
2019-12-19  6:10 ` [PATCH bpf-next v2 5/8] xdp: make devmap " Björn Töpel
2020-01-07 17:58   ` John Fastabend
2020-01-08 10:16     ` Björn Töpel
2020-01-08 10:23       ` Toke Høiland-Jørgensen
2020-01-08 10:25         ` Björn Töpel
2019-12-19  6:10 ` [PATCH bpf-next v2 6/8] xdp: make cpumap " Björn Töpel
2020-01-07 17:59   ` John Fastabend
2019-12-19  6:10 ` [PATCH bpf-next v2 7/8] xdp: remove map_to_flush and map swap detection Björn Töpel
2020-01-07 18:15   ` John Fastabend
2020-01-07 21:07     ` Toke Høiland-Jørgensen
2020-01-08  3:45       ` John Fastabend
2020-01-08 10:24         ` Björn Töpel
2019-12-19  6:10 ` [PATCH bpf-next v2 8/8] xdp: simplify __bpf_tx_xdp_map() Björn Töpel
2019-12-19  7:18 ` [PATCH bpf-next v2 0/8] Simplify xdp_do_redirect_map()/xdp_do_flush_map() and XDP maps Jesper Dangaard Brouer
2019-12-20  5:21 ` Alexei Starovoitov
2019-12-20  7:46   ` Jesper Dangaard Brouer
2019-12-20  9:26     ` Jesper Dangaard Brouer
2019-12-20 10:29       ` Toke Høiland-Jørgensen
2020-01-07 11:10         ` Björn Töpel
2020-01-07 11:25           ` Toke Høiland-Jørgensen
2020-01-07 13:05             ` Jesper Dangaard Brouer
2020-01-07 13:27               ` Toke Høiland-Jørgensen
2020-01-07 13:52                 ` Jesper Dangaard Brouer
2020-01-07 14:18                   ` Toke Høiland-Jørgensen

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