Messages in this thread | | | From | Namhyung Kim <> | Date | Thu, 22 Sep 2022 13:42:08 -0700 | Subject | Re: [PATCH v2] perf tools: Get a perf cgroup more portably in BPF |
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Hi Hao,
On Thu, Sep 22, 2022 at 12:36 PM Hao Luo <haoluo@google.com> wrote: > > On Wed, Sep 21, 2022 at 9:40 PM Namhyung Kim <namhyung@kernel.org> wrote: > > > > The perf_event_cgrp_id can be different on other configurations. > > To be more portable as CO-RE, it needs to get the cgroup subsys id > > using the bpf_core_enum_value() helper. > > > > I remember using bpf_core_enum_value requires a compiler built-in. So > the build will fail on old compiler such as clang-11. See [1]. Maybe > we should surround it with #if > __has_builtin(__builtin_preserve_enum_value) to be sure. > > [1] https://www.spinics.net/lists/bpf/msg30859.html
Thanks for pointing this out. As this is a kind of optimization I think we can fallback to using the existing value if not available. Will send v3.
Thanks, Namhyung
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