linux-kernel - Re: [PATCH] fix linux kernel BTF builds: increase max percpu variables by 10x

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Message-ID: <f248cf92-038c-480f-b077-f7d56ebc55bc@nvidia.com>
Date: Thu, 29 Feb 2024 10:15:23 -0800
From: John Hubbard <jhubbard@...dia.com>
To: Alan Maguire <alan.maguire@...cle.com>, Jiri Olsa <olsajiri@...il.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>,
 Alexei Starovoitov <ast@...nel.org>, bpf@...r.kernel.org,
 LKML <linux-kernel@...r.kernel.org>, dwarves@...r.kernel.org
Subject: Re: [PATCH] fix linux kernel BTF builds: increase max percpu
 variables by 10x

> ...
> Running
> 
> bpftool btf dump file vmlinux |grep "] VAR"
> 

$ bpftool btf dump file vmlinux |grep "] VAR" | wc -l
4852

$ bpftool btf dump file vmlinux |grep "] VAR" | tail -5
[136994] VAR '_alloc_tag_cntr.9' type_id=703, linkage=static
[137003] VAR '_alloc_tag_cntr.5' type_id=703, linkage=static
[137004] VAR '_alloc_tag_cntr.7' type_id=703, linkage=static
[137005] VAR '_alloc_tag_cntr.17' type_id=703, linkage=static
[137018] VAR '_alloc_tag_cntr.14' type_id=703, linkage=static

> ...should give us a sense of what's going on. I only see 375 per-cpu
> variables when I do this so maybe there's something
> kernel-config-specific that might explain why you have so many more?

Yes, as mentioned earlier, this is specifically due to the .config.
The .config is a huge distro configuration that has a lot of modules
enabled.


thanks,
-- 
John Hubbard
NVIDIA