[PATCH v6] erofs: free pclusters if no cached folio is attached

[Gao Xiang]

On 2024/11/12 12:32, Chunhai Guo wrote:
> Once a pcluster is fully decompressed and there are no attached cached
> folios, its corresponding `struct z_erofs_pcluster` will be freed. This
> will significantly reduce the frequency of calls to erofs_shrink_scan()
> and the memory allocated for `struct z_erofs_pcluster`.
> 
> The tables below show approximately a 96% reduction in the calls to
> erofs_shrink_scan() and in the memory allocated for `struct
> z_erofs_pcluster` after applying this patch. The results were obtained
> by performing a test to copy a 4.1GB partition on ARM64 Android devices
> running the 6.6 kernel with an 8-core CPU and 12GB of memory.
> 
> 1. The reduction in calls to erofs_shrink_scan():
> +-----------------+-----------+----------+---------+
> |                 | w/o patch | w/ patch |  diff   |
> +-----------------+-----------+----------+---------+
> | Average (times) |   11390   |   390    | -96.57% |
> +-----------------+-----------+----------+---------+
> 
> 2. The reduction in memory released by erofs_shrink_scan():
> +-----------------+-----------+----------+---------+
> |                 | w/o patch | w/ patch |  diff   |
> +-----------------+-----------+----------+---------+
> | Average (Byte)  | 133612656 | 4434552  | -96.68% |
> +-----------------+-----------+----------+---------+
> 
> Signed-off-by: Chunhai Guo <guochunhai at vivo.com>

Reviewed-by: Gao Xiang <hsiangkao at linux.alibaba.com>

Thanks,
Gao Xiang