Messages in this thread | | | Date | Mon, 5 Jul 2021 08:59:01 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH] kretprobe scalability improvement |
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On Sun, 4 Jul 2021 10:16:47 +0100 Christoph Hellwig <hch@infradead.org> wrote:
> Would it make sense to just reuse kernel/bpf/percpu_freelist.c for > kretprobes?
Hmm, I don't think so. It seems that what Wuqiang proposed is more efficient than the percpu_freelist, and it will be less efficient from the viewpoint of memory usage because kretprobe freelist manages instance pool among all CPUs (which can be unbalanced, sometimes 95% used by one core, sometimes used evenly).
Actually, the best solution is to have per-task fixed-size instance pool which is shared by all kretprobes (e.g. 4kb/task), because the instance makes a "shadow stack" for each task. This may consume more memory but is not increased by adding kretprobes, and should be scalable.
Thank you,
-- Masami Hiramatsu <mhiramat@kernel.org>
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