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iovisor / bcc

BCC - Tools for BPF-based Linux IO analysis, networking, monitoring, and more
Apache License 2.0
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Fix slabratetop.py for 6.8 kernel #4940

Closed yonghong-song closed 6 months ago

yonghong-song commented 6 months ago

slabratetop.py failed with 6.8 kernel with

      /virtual/main.c:100:10: fatal error: 'linux/slub_def.h' file not found
        100 | #include <linux/slub_def.h>
            |          ^~~~~~~~~~~~~~~~~~
      1 error generated.

Actually 'kmem_cache' is also not available to bcc any more. We already copied 'slab' data structure to bcc, copying yet another one (probably with others) will make things too complex and error prone.

Let us use newly introduced kernel_struct_field_size_offset() API. We could get some data structure (field, size) information from kernel BTF. This enables us to work around header file not available issue.

yonghong-song commented 6 months ago

cc @jeromemarchand

yonghong-song commented 6 months ago

this is fragile. Why do we need this .py based tool when we already have one based on vmlinux.h, libbpf, and CORE. Doing mini-CORE like logic specific for this tool will be challenging to maintain. I'd just delete this slabratetop.py

Okay, I will abandon this patch. But since this patch is to address an issue with 6.8 kernel which is just release a week ago and has not made into the main distribution yet. I think we do not need to delete it now. Instead of this patch, I will have another patch to warn user that >= 6.8 release won't work and suggest user to use libbpf tool version slabratetop. The tool itself will be moved to 'old' directory at some point in the future when most users won't be able to use it any more.