From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: "Kumar Kartikeya Dwivedi" <memxor@gmail.com>, <bpf@vger.kernel.org>
Cc: "Andrii Nakryiko" <andrii@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Eduard Zingerman" <eddyz87@gmail.com>,
"Emil Tsalapatis" <emil@etsalapatis.com>,
"Tejun Heo" <tj@kernel.org>, <kkd@meta.com>,
<kernel-team@meta.com>
Subject: Re: [PATCH bpf-next v2 2/5] bpf: Add file descriptor interface for program streams
Date: Thu, 24 Sep 2026 21:11:47 +0000 [thread overview]
Message-ID: <DLNUTL0UJVKC.NN3B416MJ0BI@gmail.com> (raw)
In-Reply-To: <20260924162641.1922423-3-memxor@gmail.com>
On Thu, Sep 24, 2026 at 06:26 PM Kumar Kartikeya Dwivedi <memxor@gmail.com> wrote:
> +static void bpf_stream_publish(struct bpf_stream *stream, int len)
> +{
> + /* Pairs with atomic_read_acquire() in bpf_stream_readable_bytes(). */
> + (void)atomic_add_return_release(len, &stream->readable);
> + bpf_stream_queue_notify(stream);
> +}
This queues irq_work on every bpf_stream_vprintk() and every stage
commit, whether anyone opened the stream or not.
That's an irq_work interrupt per print for every existing user.
ringbuf queues it only when the consumer caught up.
The result of atomic_add_return_release() is thrown away.
can we queue the work only when it returns len, i.e. when the stream
was empty ?
pw-bot: cr
next prev parent reply other threads:[~2026-09-24 21:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-24 16:26 [PATCH bpf-next v2 0/5] File descriptor interface for BPF streams Kumar Kartikeya Dwivedi
2026-09-24 16:26 ` [PATCH bpf-next v2 1/5] bpf: Skip zero-length stream writes Kumar Kartikeya Dwivedi
2026-09-24 16:26 ` [PATCH bpf-next v2 2/5] bpf: Add file descriptor interface for program streams Kumar Kartikeya Dwivedi
2026-09-24 21:11 ` Alexei Starovoitov [this message]
2026-09-24 16:26 ` [PATCH bpf-next v2 3/5] libbpf: Add bpf_prog_stream_open() Kumar Kartikeya Dwivedi
2026-09-24 16:26 ` [PATCH bpf-next v2 4/5] bpftool: Read program streams through file descriptors Kumar Kartikeya Dwivedi
2026-09-24 21:12 ` Alexei Starovoitov
2026-09-24 16:26 ` [PATCH bpf-next v2 5/5] selftests/bpf: Test program stream " Kumar Kartikeya Dwivedi
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