linux-kernel - Re: [PATCH bpf-next 1/2] bpf: Add ability to pin bpf timer to calling CPU

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Date:   Tue, 3 Oct 2023 18:06:55 +0000
From:   Song Liu <songliubraving@...a.com>
To:     David Vernet <void@...ifault.com>
CC:     bpf <bpf@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        "martin.lau@...ux.dev" <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>,
        Yonghong Song <yonghong.song@...ux.dev>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Kernel Team <kernel-team@...a.com>,
        "himadrispandya@...il.com" <himadrispandya@...il.com>,
        "julia.lawall@...ia.fr" <julia.lawall@...ia.fr>
Subject: Re: [PATCH bpf-next 1/2] bpf: Add ability to pin bpf timer to calling
 CPU



> On Oct 2, 2023, at 4:47 PM, David Vernet <void@...ifault.com> wrote:
> 
> BPF supports creating high resolution timers using bpf_timer_* helper
> functions. Currently, only the BPF_F_TIMER_ABS flag is supported, which
> specifies that the timeout should be interpreted as absolute time. It
> would also be useful to be able to pin that timer to a core. For
> example, if you wanted to make a subset of cores run without timer
> interrupts, and only have the timer be invoked on a single core.
> 
> This patch adds support for this with a new BPF_F_TIMER_CPU_PIN flag.
> When specified, the HRTIMER_MODE_PINNED flag is passed to
> hrtimer_start(). A subsequent patch will update selftests to validate.
> 
> Signed-off-by: David Vernet <void@...ifault.com>

Acked-by: Song Liu <song@...nel.org>