On Tue, Sep 05, 2023 at 05:32:15AM +0000, liwenyu01@xxxxxxxxxxxx wrote: > >> reclaim of the task in do_try_to_free_pages(). In systems with NUMA > >> open, some tasks occasionally experience slower response times, but the > >> total count of reclaim does not increase, using ftrace can show that > >> node_reclaim has occurred. > >> > >> The memory reclaim occurring in get_page_from_freelist() is also due to > >> heavy memory load. To get the impact of tasks in memory reclaim, this > >> patch adds the statistics of the memory reclaim delay statistics for > >> __node_reclaim(). > >> > >> ... > >> > >> --- a/mm/vmscan.c > >> +++ b/mm/vmscan.c > >> @@ -8010,6 +8010,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in > >> > >> cond_resched(); > >> psi_memstall_enter(&pflags); > >> + delayacct_freepages_start(); > >> fs_reclaim_acquire(sc.gfp_mask); > >> /* > >> * We need to be able to allocate from the reserves for RECLAIM_UNMAP > >> @@ -8032,6 +8033,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in > >> memalloc_noreclaim_restore(noreclaim_flag); > >> fs_reclaim_release(sc.gfp_mask); > >> psi_memstall_leave(&pflags); > >> + delayacct_freepages_end(); > >> > >> trace_mm_vmscan_node_reclaim_end(sc.nr_reclaimed); > > > > __node_reclaim() calls shrink_node() which at some point will call > > do_try_to_free_pages() (yes?), which calls delayacct_freepages_start(). > > > > So we're effectively nesting calls to delayacct_freepages_start(), > > which isn't designed for that? > > > sorry, the last reply was a mistake. > > It seems that no point in shrink_node() will call do_try_to_free_pages(). > And do_try_to_free_pages() will call shrink_node() through shrink_zones(), > if shrink_node() also has some point will call do_try_to_free_pages,then > delayacct_freepages_start() is nested now? That's because shrink_node() goes through shrink_list() via shrink_lruvec()? do_try_to_free_pages() will call shrink_node(). Ideally we should have some counters around __node_reclaim() and balance_pgdat() like psi_memstall_* does. Do you want to mimic what psi_memstall_* does? This would change the definition of delayacct free pages, but I don't think it will make it worse. Balbir Singh
