Re: [PATCH dwarves v2 07/10] btf_encoder: introduce btf_encoding_context

[Eduard Zingerman <eddyz87@gmail.com>]

On Fri, 2024-12-13 at 22:37 +0000, Ihor Solodrai wrote:
> Introduce a static struct holding global data necessary for BTF
> encoding: elf_functions tables and btf_encoder structs.
> 
> The context has init()/exit() interface that should be used to
> indicate when BTF encoding work has started and ended.
> 
> I considered freeing everything contained in the context exclusively
> on exit(), however it turns out this unnecessarily increases max
> RSS. Probably because the work done in btf_encoder__encode() requires
> relatively more memory, and if encoders and tables are freed earlier,
> that space is reused.
> 
> Compare:
>     -j4: 	Maximum resident set size (kbytes): 868484
>     -j8: 	Maximum resident set size (kbytes): 1003040
>     -j16: 	Maximum resident set size (kbytes): 1039416
>     -j32: 	Maximum resident set size (kbytes): 1145312
> vs
>     -j4: 	Maximum resident set size (kbytes): 972692
>     -j8: 	Maximum resident set size (kbytes): 1043184
>     -j16: 	Maximum resident set size (kbytes): 1081156
>     -j32: 	Maximum resident set size (kbytes): 1218184
> 
> Signed-off-by: Ihor Solodrai <ihor.solodrai@pm.me>
> ---

After patch #10 "dwarf_loader: multithreading with a job/worker model"
from this series I do not understand why this patch is necessary.
After patch #10 there is only one BTF encoder, thus:
- there is no need to track btf_encoder_list;
- elf_functions_list can now be a part of the encoder;
- it should be possible to forgo global variable for encoder
  and pass it as a parameter for each btf_encoder__* func.

So it seems that this patch should be dropped and replaced by one that
follows patch #10 and applies the above simplifications.
Wdyt?

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