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From: Gilad Reti <gilad.reti@gmail.com>
To: bpf <bpf@vger.kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>, assaf.piltzer@cyberark.com
Subject: libbpf ringbuf manager starvation
Date: Tue, 19 Jan 2021 17:51:10 +0200	[thread overview]
Message-ID: <CANaYP3ENW8FV=CsKFmvpqCvbwzz5z2dLmBzrsO9QePVPuyaxXQ@mail.gmail.com> (raw)

Hello there,

When playing with the (relatively) new ringbuf api we encountered
something that we believe can be an interesting usecase.
When registering multiple rinbufs to the same ringbuf manager, one of
which is highly active, other ringbufs may starve. Since libbpf
(e)polls on all the managed ringbufs at once and then tries to read
*as many samples as it can* from ready ringbufs, it may get stuck
indefinitely on one of them, not being able to process the other.
We know that the current ringbuf api exposes the epoll_fd so that one
can implement the epoll logic on his own, but this sounds to us like a
not so advanced usecase that may be worth taking care of specifically.
Does allowing to specify a maximum number of samples to consume sounds
like a reasonable addition to the ringbuf api?

Thanks

             reply	other threads:[~2021-01-19 15:53 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-19 15:51 Gilad Reti [this message]
2021-01-21  7:29 ` libbpf ringbuf manager starvation Andrii Nakryiko
2021-01-21 21:42   ` Gilad Reti

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