Re: [PATCH v1 0/3] Fix and improve __maps__fixup_overlap_and_insert

[James Clark]

On 21/05/2024 17:51, Ian Rogers wrote:
> Fix latent unlikely bugs in __maps__fixup_overlap_and_insert.
> 
> Improve __maps__fixup_overlap_and_insert's performance 21x in the case
> of overlapping mmaps. sesse@xxxxxxxxxx reported slowness opening
> perf.data files from chromium where the files contained a large number
> of overlapping mappings. Improve this case primarily by avoiding
> unnecessary sorting.
> 
> Unscientific timing data processing a perf.data file with overlapping
> mmap events from chromium:
> 
> Before:
> real    0m9.856s
> user    0m9.637s
> sys     0m0.204s
> 
> After:
> real    0m0.675s
> user    0m0.454s
> sys     0m0.196s
> 
> Tested with address/leak sanitizer, invariant checks and validating
> the before and after output are identical.
> 
> Ian Rogers (3):
>   perf maps: Fix use after free in __maps__fixup_overlap_and_insert
>   perf maps: Reduce sorting for overlapping mappings
>   perf maps: Add/use a sorted insert for fixup overlap and insert
> 
>  tools/perf/util/maps.c | 113 +++++++++++++++++++++++++++++++++--------
>  1 file changed, 92 insertions(+), 21 deletions(-)
> 

Reviewed-by: James Clark <james.clark@xxxxxxx>

I'm wondering if there is any point in the non sorted insert any more?

Maps could be always either sorted by name or sorted by address and
insert() is always a sorted/fixup-overlaps insert depending on the sort
style of the list.