commit ee1174acb78fef9cbe8821f0afdb7c9951561430
author Chia-hung Duan <chiahungduan@google.com> Mon Aug 21 17:26:41 2023 +0000
committer Copybara-Service <copybara-worker@google.com> Mon Aug 21 10:35:40 2023 -0700
tree efa052aaff0cce3e8b983abdf4b5840eebe0286e
parent 75abbb531244aa1f2a90c7b603817a90bae4ade4

[scudo] Support dumping fragmentation data in SizeClassAllocator64

This tells the number of pages that still have blocks in-used, i.e.,
those pages can't do releaseToOSMaybe(). Along with the information of
getStats() and RSS usage from the system (like smaps), we can tell if
the heuristic in releaseToOSMaybe() works well in certain scenarios.

Here's the sample output:
```
    Fragmentation Stats: SizeClassAllocator64: page size = 4096
      01 (    32): inuse/total blocks:    275/   416 inuse/total pages:      4/     4 inuse bytes:     16K
      02 (    48): inuse/total blocks:    182/   312 inuse/total pages:      4/     4 inuse bytes:     16K
      03 (    64): inuse/total blocks:    169/   312 inuse/total pages:      5/     5 inuse bytes:     20K
      ...
      32 (  1040): inuse/total blocks:     90/   152 inuse/total pages:     37/    39 inuse bytes:    148K
      33 (  1168): inuse/total blocks:    136/   232 inuse/total pages:     64/    67 inuse bytes:    256K
      34 (  1296): inuse/total blocks:    138/   226 inuse/total pages:     68/    72 inuse bytes:    272K
      35 (  1424): inuse/total blocks:    140/   232 inuse/total pages:     78/    81 inuse bytes:    312K
      36 (  1552): inuse/total blocks:    157/   248 inuse/total pages:     89/    94 inuse bytes:    356K
      ...
```

SizeClassAllocator32 requires further refactoring to support this.

Reviewed By: cferris

Differential Revision: https://reviews.llvm.org/D158225

GitOrigin-RevId: 5f771c9936b828d5fc017ad558e84702500df99c