Re: [PATCH bpf-next 0/2] Allow mmap of /sys/kernel/btf/vmlinux

[Daniel Xu]

On Thu, May 1, 2025, at 7:28 AM, Lorenz Bauer wrote:
> I'd like to cut down the memory usage of parsing vmlinux BTF in ebpf-go.
> With some upcoming changes the library is sitting at 5MiB for a parse.
> Most of that memory is simply copying the BTF blob into user space.
> By allowing vmlinux BTF to be mmapped read-only into user space I can
> cut memory usage by about 75%.

Cool! Maybe teach libbpf to use this as well? So everyone else can pick up
the win transparently.

>
> Signed-off-by: Lorenz Bauer <lmb@xxxxxxxxxxxxx>
> ---
> Lorenz Bauer (2):
>       btf: allow mmap of vmlinux btf
>       selftests: bpf: add a test for mmapable vmlinux BTF
>
>  include/asm-generic/vmlinux.lds.h                  |  3 +-
>  kernel/bpf/sysfs_btf.c                             | 25 ++++++-
>  tools/testing/selftests/bpf/prog_tests/btf_sysfs.c | 79 ++++++++++++++++++++++
>  3 files changed, 104 insertions(+), 3 deletions(-)
> ---
> base-commit: 38d976c32d85ef12dcd2b8a231196f7049548477
> change-id: 20250501-vmlinux-mmap-2ec5563c3ef1
>
> Best regards,
> -- 
> Lorenz Bauer <lmb@xxxxxxxxxxxxx>