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From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Mon, 13 Sep 2021 10:59:55 -0700
Message-ID: <CAADnVQLLYQwMh-jUa7pJH9uwAhEyVhc1gGR+cnS_s-4YTPqpTQ@mail.gmail.com>
Subject: Re: [PATCH v7 bpf-next 0/3] bpf: introduce bpf_get_branch_snapshot
To:     Song Liu <songliubraving@fb.com>
Cc:     bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>, kjain@linux.ibm.com,
        Kernel Team <kernel-team@fb.com>
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On Fri, Sep 10, 2021 at 11:34 AM Song Liu <songliubraving@fb.com> wrote:
>
> Changes v6 => v7:
> 1. Improve/fix intel_pmu_snapshot_branch_stack() logic. (Peter).
>
> Branch stack can be very useful in understanding software events. For
> example, when a long function, e.g. sys_perf_event_open, returns an errno,
> it is not obvious why the function failed. Branch stack could provide very
> helpful information in this type of scenarios.
>
> This set adds support to read branch stack with a new BPF helper
> bpf_get_branch_trace(). Currently, this is only supported in Intel systems.
> It is also possible to support the same feaure for PowerPC.

Applied. Thanks