On Wed, Mar 20, 2024 at 02:08:22AM +0000, Yosry Ahmed wrote: > Currently, the number of protected zswap entries corresponding to an > lruvec are incremented every time we swapin a page. Correct. This is the primary signal that the shrinker is being too aggressive in moving entries to disk and should slow down...? > This happens regardless of whether or not the page originated in > zswap. Hence, swapins from disk will lead to increasing protection > on potentially stale zswap entries. Furthermore, the increased > shrinking protection can lead to more pages skipping zswap and going > to disk, eventually leading to even more swapins from disk and > starting a vicious circle. How does shrinker protection affect zswap stores? On the contrary, I would expect this patch to create a runaway shrinker. The more aggressively it moves entries out to disk, the lower the rate of zswap loads, the more aggressively it moves more entries out to disk. > Instead, only increase the protection when pages are loaded from zswap. > This also has a nice side effect of removing zswap_folio_swapin() and > replacing it with a static helper that is only called from zswap_load(). > > No problems were observed in practice, this was found through code > inspection. This is missing test results :)
