On 2024/1/18 23:11, Johannes Weiner wrote: > On Wed, Jan 17, 2024 at 09:23:19AM +0000, Chengming Zhou wrote: >> Each swapfile has one rb-tree to search the mapping of swp_entry_t to >> zswap_entry, that use a spinlock to protect, which can cause heavy lock >> contention if multiple tasks zswap_store/load concurrently. >> >> Optimize the scalability problem by splitting the zswap rb-tree into >> multiple rb-trees, each corresponds to SWAP_ADDRESS_SPACE_PAGES (64M), >> just like we did in the swap cache address_space splitting. >> >> Although this method can't solve the spinlock contention completely, it >> can mitigate much of that contention. Below is the results of kernel build >> in tmpfs with zswap shrinker enabled: >> >> linux-next zswap-lock-optimize >> real 1m9.181s 1m3.820s >> user 17m44.036s 17m40.100s >> sys 7m37.297s 4m54.622s >> >> So there are clearly improvements. >> >> Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx> > > Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> > > One minor nit: > >> @@ -265,6 +266,10 @@ static bool zswap_has_pool; >> * helpers and fwd declarations >> **********************************/ >> >> +#define swap_zswap_tree(entry) \ >> + (&zswap_trees[swp_type(entry)][swp_offset(entry) \ >> + >> SWAP_ADDRESS_SPACE_SHIFT]) > > Make this a static inline function instead? Good suggestion, will do. Thanks.
