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[212.51.140.210]) by smtp.gmail.com with ESMTPSA id k17-20020a7bc311000000b003fc02218d6csm4024695wmj.25.2023.07.27.01.31.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Jul 2023 01:31:15 -0700 (PDT) Date: Thu, 27 Jul 2023 10:31:15 +0200 From: Adam Sindelar To: Hou Tao Cc: bpf@vger.kernel.org, Adam Sindelar , David Vernet , Brendan Jackman , KP Singh , linux-kernel@vger.kernel.org, Alexei Starovoitov , Florent Revest , Andrii Nakryiko Subject: Re: [PATCH] libbpf: Expose API to consume one ring at a time Message-ID: References: <20230725162654.912897-1-adam@wowsignal.io> <482ed32c-5650-54a5-d5bb-18b9bb03e838@huaweicloud.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <482ed32c-5650-54a5-d5bb-18b9bb03e838@huaweicloud.com> X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_NONE, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Thu, Jul 27, 2023 at 02:17:12PM +0800, Hou Tao wrote: > Hi, > > On 7/27/2023 9:06 AM, Hou Tao wrote: > > Hi, > > > > On 7/26/2023 12:26 AM, Adam Sindelar wrote: > >> We already provide ring_buffer__epoll_fd to enable use of external > >> polling systems. However, the only API available to consume the ring > >> buffer is ring_buffer__consume, which always checks all rings. When > >> polling for many events, this can be wasteful. > >> > >> Signed-off-by: Adam Sindelar > >> --- > >> tools/lib/bpf/libbpf.h | 1 + > >> tools/lib/bpf/ringbuf.c | 15 +++++++++++++++ > >> 2 files changed, 16 insertions(+) > >> > >> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h > >> index 55b97b2087540..20ccc65eb3f9d 100644 > >> --- a/tools/lib/bpf/libbpf.h > >> +++ b/tools/lib/bpf/libbpf.h > >> @@ -1195,6 +1195,7 @@ LIBBPF_API int ring_buffer__add(struct ring_buffer *rb, int map_fd, > >> ring_buffer_sample_fn sample_cb, void *ctx); > >> LIBBPF_API int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms); > >> LIBBPF_API int ring_buffer__consume(struct ring_buffer *rb); > >> +LIBBPF_API int ring_buffer__consume_ring(struct ring_buffer *rb, uint32_t ring_id); > >> LIBBPF_API int ring_buffer__epoll_fd(const struct ring_buffer *rb); > >> > >> struct user_ring_buffer_opts { > >> diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c > >> index 02199364db136..8d087bfc7d005 100644 > >> --- a/tools/lib/bpf/ringbuf.c > >> +++ b/tools/lib/bpf/ringbuf.c > >> @@ -290,6 +290,21 @@ int ring_buffer__consume(struct ring_buffer *rb) > >> return res; > >> } > >> > >> +/* Consume available data from a single RINGBUF map identified by its ID. > >> + * The ring ID is returned in epoll_data by epoll_wait when called with > >> + * ring_buffer__epoll_fd. > >> + */ > >> +int ring_buffer__consume_ring(struct ring_buffer *rb, uint32_t ring_id) > >> +{ > >> + struct ring *ring; > >> + > >> + if (ring_id >= rb->ring_cnt) > >> + return libbpf_err(-EINVAL); > >> + > >> + ring = &rb->rings[ring_id]; > >> + return ringbuf_process_ring(ring); > > When ringbuf_process_ring() returns an error, we need to use > > libbpf_err() to set the errno accordingly. > > It seems that even when ringbuf_process_ring() returns a positive > result, we also need to cap it under INT_MAX, otherwise it may be cast > into a negative error. Ah, sorry I missed that. Fixed in v3, going out in a few moments. > >> +} > >> + > >> /* Poll for available data and consume records, if any are available. > >> * Returns number of records consumed (or INT_MAX, whichever is less), or > >> * negative number, if any of the registered callbacks returned error. > > > > > > . > Thanks!