Re: [PATCH 05/10] perf jevents: Add block-indexed string packing and --compress=zlib

[sashiko-bot@kernel.org]

> Compressing big_c_string (~6.9 MiB on x86) as a single monolithic stream
> would force perf to allocate and decompress megabytes of unused CPU
> models' strings on startup just to look up a single event or metric,
> whereas compressing each short string individually suffers from poor
> compression ratios and per-string framing overhead.
> 
> Introduce "block-indexed string compression" via a --compress=<formats>
> option to jevents.py (defaulting to 'none'):
> - Sorted, non-folded BigCString byte records are packed sequentially
>   into ~8 KiB blocks without splitting any multi-field event or metric
>   record across a block boundary (with suffix-folded strings inheriting
>   their parent record's block and intra-block offset plus suffix delta).
> - Each block is compressed independently into big_c_string_blob[],
>   indexed by big_c_string_block_offsets[] and big_c_string_raw_lens[],
>   while sharing a common dictionary across blocks so ~8 KiB blocks
> [ ... ]
> --compress=zlib shrinks pmu-events-string.o from ~6.90 MB to ~716 KB
> (~9.6x reduction) while only decompressing touched 8 KiB blocks on
> demand.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261113210822.3112700-1-irogers@google.com?part=5