zswap will try to shrink pool when zswap is full. This commit add shrink_enabled that can disable swap shrink to increase store performance. User can disable swap shrink if care about the store performance. For example in a VM with 1 CPU 1G memory 4G swap: echo lz4 > /sys/module/zswap/parameters/compressor echo z3fold > /sys/module/zswap/parameters/zpool echo 0 > /sys/module/zswap/parameters/same_filled_pages_enabled echo 1 > /sys/module/zswap/parameters/enabled usemem -a -n 1 $((4000 * 1024 * 1024)) 4718592000 bytes / 114937822 usecs = 40091 KB/s 101700 usecs to free memory echo 0 > /sys/module/zswap/parameters/shrink_enabled usemem -a -n 1 $((4000 * 1024 * 1024)) 4718592000 bytes / 8837320 usecs = 521425 KB/s 129577 usecs to free memory The store speed increased when zswap shrink disabled. Signed-off-by: Hui Zhu <teawaterz@xxxxxxxxxxxxxxxxx> --- mm/zswap.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/zswap.c b/mm/zswap.c index 46a3223..731e3d1e 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -114,6 +114,10 @@ static bool zswap_same_filled_pages_enabled = true; module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled, bool, 0644); +/* Enable/disable zswap shrink (enabled by default) */ +static bool zswap_shrink_enabled = true; +module_param_named(shrink_enabled, zswap_shrink_enabled, bool, 0644); + /********************************* * data structures **********************************/ @@ -947,6 +951,9 @@ static int zswap_shrink(void) struct zswap_pool *pool; int ret; + if (!zswap_shrink_enabled) + return -EPERM; + pool = zswap_pool_last_get(); if (!pool) return -ENOENT; -- 2.7.4
