On Tue, Dec 17, 2019 at 7:56 PM Michal Hocko <mhocko@xxxxxxxxxx> wrote:
>
> On Tue 17-12-19 06:29:15, Yafang Shao wrote:
> > On my server there're some running MEMCGs protected by memory.{min, low},
> > but I found the usage of these MEMCGs abruptly became very small, which
> > were far less than the protect limit. It confused me and finally I
> > found that was because of inode stealing.
>
> What do you mean by this exactly. Are those inodes reclaimed by the
> regular memory reclaim or by other means? Because shrink_node does
> exclude shrinking slab for protected memcgs.
By the regular memory reclaim, kswapd, direct reclaimer or memcg reclaimer.
IOW, the current->reclaim_state it set.
Take an example for you.
kswapd
balance_pgdat
shrink_node_memcgs
switch (mem_cgroup_protected) <<<< memory.current= 1024M
memory.min = 512M a file has 800M page caches
case MEMCG_PROT_NONE: <<<< hard limit is not reached.
beak;
shrink_lruvec
shrink_slab <<< it may free the inode and the free all its
page caches (800M)
Hope it could clarify.
Thanks
Yafang
