kallsyms: cache bpf symbols to avoid quadratic iteration by kernel-patches-daemon-bpf[bot] · Pull Request #10892 · kernel-patches/bpf

kernel-patches-daemon-bpf · 2026-01-30T04:59:09Z

Pull request for series with
subject: kallsyms: cache bpf symbols to avoid quadratic iteration
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807

kernel-patches-daemon-bpf · 2026-01-30T04:59:11Z

Upstream branch: 95dbe21
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-01-30T20:24:32Z

Upstream branch: b18a761
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-01-30T20:34:48Z

Upstream branch: cd77618
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-01-30T21:54:43Z

Upstream branch: c7fbf8d
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-01-31T05:25:06Z

Upstream branch: cda0cbf
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-01-31T21:53:54Z

Upstream branch: f0b5b3d
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-01-31T22:03:05Z

Upstream branch: 4bebb99
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-02-02T16:07:48Z

Upstream branch: 6b95cc5
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-02-03T00:18:45Z

Upstream branch: 6b95cc5
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-02-03T18:44:19Z

Upstream branch: f941479
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-02-03T19:06:29Z

Upstream branch: f11f7cf
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-02-04T01:07:30Z

Upstream branch: b28dac3
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-02-04T17:54:04Z

Upstream branch: 78a1605
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-02-04T18:37:53Z

Upstream branch: 5e6e1dc
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-02-04T21:28:03Z

Upstream branch: 4af5266
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-02-04T21:49:11Z

Upstream branch: 6e951a9
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

kernel-patches-daemon-bpf · 2026-02-05T02:24:39Z

Upstream branch: 75cd3be
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1048807
version: 1

The existing code iterates the whole list of bpf ksyms until the right one is found, which means quadratic complexity on top of linked list pointer chasing under rcu. This is't noticeable for most installations, but when one has 10000 bpf programs loaded, things start to add up and reading from `/proc/kallsyms` slows down a lot. Instead of doing that, we can cache the list of bpf symbols in linear time when `/proc/kallsyms` is opened, which makes the whole thing fast. Reading `/proc/kallsyms` on Apple M3 Pro in a VM and measuring system time: Before: * 15 bpf symbols: ~35ms * 10015 bpf symbols: ~1250ms After: * 15 bpf symbols: ~35ms * 10015 bpf symbols: ~50ms Testing in production on v6.12 series (with ~10000 bpf ksyms as well): * On AMD EPYC 9684X (Zen4): ~870ms -> ~100ms * On Ampere Altra Max M128-30: ~4650ms -> ~70ms Signed-off-by: Ivan Babrou <[email protected]>

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