diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/cgroup-v2.rst | 15 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/zswap.rst | 10 |
2 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 3f85254f3cef..5ec7dd753cd1 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -1679,6 +1679,21 @@ PAGE_SIZE multiple when read back. limit, it will refuse to take any more stores before existing entries fault back in or are written out to disk. + memory.zswap.writeback + A read-write single value file. The default value is "1". The + initial value of the root cgroup is 1, and when a new cgroup is + created, it inherits the current value of its parent. + + When this is set to 0, all swapping attempts to swapping devices + are disabled. This included both zswap writebacks, and swapping due + to zswap store failures. If the zswap store failures are recurring + (for e.g if the pages are incompressible), users can observe + reclaim inefficiency after disabling writeback (because the same + pages might be rejected again and again). + + Note that this is subtly different from setting memory.swap.max to + 0, as it still allows for pages to be written to the zswap pool. + memory.pressure A read-only nested-keyed file. diff --git a/Documentation/admin-guide/mm/zswap.rst b/Documentation/admin-guide/mm/zswap.rst index 62fc244ec702..b42132969e31 100644 --- a/Documentation/admin-guide/mm/zswap.rst +++ b/Documentation/admin-guide/mm/zswap.rst @@ -153,6 +153,16 @@ attribute, e. g.:: Setting this parameter to 100 will disable the hysteresis. +Some users cannot tolerate the swapping that comes with zswap store failures +and zswap writebacks. Swapping can be disabled entirely (without disabling +zswap itself) on a cgroup-basis as follows: + + echo 0 > /sys/fs/cgroup/<cgroup-name>/memory.zswap.writeback + +Note that if the store failures are recurring (for e.g if the pages are +incompressible), users can observe reclaim inefficiency after disabling +writeback (because the same pages might be rejected again and again). + When there is a sizable amount of cold memory residing in the zswap pool, it can be advantageous to proactively write these cold pages to swap and reclaim the memory for other use cases. By default, the zswap shrinker is disabled. |