From: Peter Zijlstra <peterz@infradead.org>
To: Usama Saqib <usama.saqib@datadoghq.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Jiri Olsa <jolsa@kernel.org>, bpf <bpf@vger.kernel.org>,
bigeasy@linutronix.de, torvalds@linux-foundation.org
Subject: Re: BPF and lazy preemption.
Date: Tue, 10 Dec 2024 16:21:56 +0100 [thread overview]
Message-ID: <20241210152156.GX35539@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <CAOzX8iy=hELHmPAeMxQ3on_6dqJmJryGgvAXRxMOijqr+Jj62w@mail.gmail.com>
On Tue, Dec 10, 2024 at 03:48:32PM +0100, Usama Saqib wrote:
> Thanks for your reply. It is correct that the problem I shared is
> already present under PREEMPT_FULL, and as such there is no new issue
> being introduced by PREEMPT_LAZY.
>
> My main concern is that if PREEMPT_LAZY is intended to become the
> default mode (please correct me if I am wrong here) before this
> problem is addressed in the BPF subsystem, then this would result in a
> big regression for us. This is especially true if distros pick up the
> changes in the intervening period. I wanted to draw attention to this
> issue so this situation does not happen.
Fair enough; I think it'll be a few releases before LAZY is in any shape
to be considered a replacement in any case. Quite a lot of cond_resched
(ab)use needs to be audited, Live-patching needs a bit of TLC and so on.
next prev parent reply other threads:[~2024-12-10 15:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-18 9:14 BPF and lazy preemption Usama Saqib
2024-12-10 13:25 ` Usama Saqib
2024-12-10 14:14 ` Peter Zijlstra
2024-12-10 14:48 ` Usama Saqib
2024-12-10 15:21 ` Peter Zijlstra [this message]
2024-12-10 19:33 ` Alexei Starovoitov
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