From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Lorenz Bauer <lmb@cloudflare.com>
Cc: "Björn Töpel" <bjorn@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
"Jakub Kicinski" <kuba@kernel.org>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
"John Fastabend" <john.fastabend@gmail.com>,
kernel-team <kernel-team@cloudflare.com>,
"Network Development" <netdev@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf-next] bpf: do not invoke the XDP dispatcher for PROG_RUN with single repeat
Date: Wed, 29 Sep 2021 14:17:01 -0700 [thread overview]
Message-ID: <CAADnVQ+UJ5bhRNdnHM62_XFzMp3q1-Njh80ZNvs=4=PH1jAmpw@mail.gmail.com> (raw)
In-Reply-To: <20210928093100.27124-1-lmb@cloudflare.com>
On Tue, Sep 28, 2021 at 2:31 AM Lorenz Bauer <lmb@cloudflare.com> wrote:
>
> We have a unit test that invokes an XDP program with 1m different
> inputs, aka 1m BPF_PROG_RUN syscalls. We run this test concurrently
> with slight variations in how we generated the input.
>
> Since commit f23c4b3924d2 ("bpf: Start using the BPF dispatcher in BPF_TEST_RUN")
> the unit test has slowed down significantly. Digging deeper reveals that
> the concurrent tests are serialised in the kernel on the XDP dispatcher.
> This is a global resource that is protected by a mutex, on which we contend.
>
> Fix this by not calling into the XDP dispatcher if we only want to perform
> a single run of the BPF program.
>
> See: https://lore.kernel.org/bpf/CACAyw9_y4QumOW35qpgTbLsJ532uGq-kVW-VESJzGyiZkypnvw@mail.gmail.com/
>
> Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Applied. Thanks
prev parent reply other threads:[~2021-09-29 21:17 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-28 9:30 [PATCH bpf-next] bpf: do not invoke the XDP dispatcher for PROG_RUN with single repeat Lorenz Bauer
2021-09-29 21:17 ` Alexei Starovoitov [this message]
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