[RFC PATCH 0/2] mm: zsmalloc: make shrinker compaction budget-aware

[xueyuan.chen@vivo.com]

From: Xueyuan Chen <xueyuan.chen@vivo.com>

zs_shrinker_scan() currently calls zs_compact(), which compacts the whole
pool regardless of sc->nr_to_scan. A single shrinker callback can therefore
reclaim much more than requested and spend a long time in compaction.

On an Android device with 12 GB of RAM, observed zsmalloc compaction
durations had a p95 of 38.86 ms and a maximum of 269.68 ms, motivating a
per-scan reclaim goal.

This series uses sc->nr_to_scan as a reclaimed-page goal and keeps a
per-pool size-class cursor so later scans resume where the previous scan
stopped. The existing full-pool behavior of zs_compact() is unchanged.

Xueyuan Chen (2):
  mm: zsmalloc: add a page limit to pool compaction
  mm: zsmalloc: use the shrinker reclaim budget

 mm/zsmalloc.c | 46 +++++++++++++++++++++++++++++++---------------
 1 file changed, 31 insertions(+), 15 deletions(-)

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2.47.3