| Message ID | 20210722182627.2267368-1-shakeelb@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | writeback: memcg: simplify cgroup_writeback_by_id | expand |
On Thu 22-07-21 11:26:27, Shakeel Butt wrote: > Currently cgroup_writeback_by_id calls mem_cgroup_wb_stats() to get > dirty pages for a memcg. However mem_cgroup_wb_stats() does a lot more > than just get the number of dirty pages. Just directly get the number of > dirty pages instead of calling mem_cgroup_wb_stats(). Also > cgroup_writeback_by_id() is only called for best-effort dirty flushing, > so remove the unused 'nr' parameter and no need to explicitly flush > memcg stats. > > Signed-off-by: Shakeel Butt <shakeelb@google.com> Looks good to me. Feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > fs/fs-writeback.c | 20 +++++++++----------- > include/linux/memcontrol.h | 15 +++++++++++++++ > include/linux/writeback.h | 2 +- > mm/memcontrol.c | 13 +------------ > 4 files changed, 26 insertions(+), 24 deletions(-) > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > index 867984e778c3..35894a2dba75 100644 > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -1039,20 +1039,20 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, > * cgroup_writeback_by_id - initiate cgroup writeback from bdi and memcg IDs > * @bdi_id: target bdi id > * @memcg_id: target memcg css id > - * @nr: number of pages to write, 0 for best-effort dirty flushing > * @reason: reason why some writeback work initiated > * @done: target wb_completion > * > * Initiate flush of the bdi_writeback identified by @bdi_id and @memcg_id > * with the specified parameters. > */ > -int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr, > +int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, > enum wb_reason reason, struct wb_completion *done) > { > struct backing_dev_info *bdi; > struct cgroup_subsys_state *memcg_css; > struct bdi_writeback *wb; > struct wb_writeback_work *work; > + unsigned long dirty; > int ret; > > /* lookup bdi and memcg */ > @@ -1081,24 +1081,22 @@ int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr, > } > > /* > - * If @nr is zero, the caller is attempting to write out most of > + * The caller is attempting to write out most of > * the currently dirty pages. Let's take the current dirty page > * count and inflate it by 25% which should be large enough to > * flush out most dirty pages while avoiding getting livelocked by > * concurrent dirtiers. > + * > + * BTW the memcg stats are flushed periodically and this is best-effort > + * estimation, so some potential error is ok. > */ > - if (!nr) { > - unsigned long filepages, headroom, dirty, writeback; > - > - mem_cgroup_wb_stats(wb, &filepages, &headroom, &dirty, > - &writeback); > - nr = dirty * 10 / 8; > - } > + dirty = memcg_page_state(mem_cgroup_from_css(memcg_css), NR_FILE_DIRTY); > + dirty = dirty * 10 / 8; > > /* issue the writeback work */ > work = kzalloc(sizeof(*work), GFP_NOWAIT | __GFP_NOWARN); > if (work) { > - work->nr_pages = nr; > + work->nr_pages = dirty; > work->sync_mode = WB_SYNC_NONE; > work->range_cyclic = 1; > work->reason = reason; > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index b4c6b613e162..7028d8e4a3d7 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -989,6 +989,16 @@ static inline void mod_memcg_state(struct mem_cgroup *memcg, > local_irq_restore(flags); > } > > +static inline unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx) > +{ > + long x = READ_ONCE(memcg->vmstats.state[idx]); > +#ifdef CONFIG_SMP > + if (x < 0) > + x = 0; > +#endif > + return x; > +} > + > static inline unsigned long lruvec_page_state(struct lruvec *lruvec, > enum node_stat_item idx) > { > @@ -1444,6 +1454,11 @@ static inline void mod_memcg_state(struct mem_cgroup *memcg, > { > } > > +static inline unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx) > +{ > + return 0; > +} > + > static inline unsigned long lruvec_page_state(struct lruvec *lruvec, > enum node_stat_item idx) > { > diff --git a/include/linux/writeback.h b/include/linux/writeback.h > index 1f34ddf284dc..109e0dcd1d21 100644 > --- a/include/linux/writeback.h > +++ b/include/linux/writeback.h > @@ -218,7 +218,7 @@ void wbc_attach_and_unlock_inode(struct writeback_control *wbc, > void wbc_detach_inode(struct writeback_control *wbc); > void wbc_account_cgroup_owner(struct writeback_control *wbc, struct page *page, > size_t bytes); > -int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr_pages, > +int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, > enum wb_reason reason, struct wb_completion *done); > void cgroup_writeback_umount(void); > bool cleanup_offline_cgwb(struct bdi_writeback *wb); > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 35bb5f8f9ea8..6580c2381a3e 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -631,17 +631,6 @@ void __mod_memcg_state(struct mem_cgroup *memcg, int idx, int val) > cgroup_rstat_updated(memcg->css.cgroup, smp_processor_id()); > } > > -/* idx can be of type enum memcg_stat_item or node_stat_item. */ > -static unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx) > -{ > - long x = READ_ONCE(memcg->vmstats.state[idx]); > -#ifdef CONFIG_SMP > - if (x < 0) > - x = 0; > -#endif > - return x; > -} > - > /* idx can be of type enum memcg_stat_item or node_stat_item. */ > static unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx) > { > @@ -4609,7 +4598,7 @@ void mem_cgroup_flush_foreign(struct bdi_writeback *wb) > atomic_read(&frn->done.cnt) == 1) { > frn->at = 0; > trace_flush_foreign(wb, frn->bdi_id, frn->memcg_id); > - cgroup_writeback_by_id(frn->bdi_id, frn->memcg_id, 0, > + cgroup_writeback_by_id(frn->bdi_id, frn->memcg_id, > WB_REASON_FOREIGN_FLUSH, > &frn->done); > } > -- > 2.32.0.432.gabb21c7263-goog >
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 867984e778c3..35894a2dba75 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1039,20 +1039,20 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, * cgroup_writeback_by_id - initiate cgroup writeback from bdi and memcg IDs * @bdi_id: target bdi id * @memcg_id: target memcg css id - * @nr: number of pages to write, 0 for best-effort dirty flushing * @reason: reason why some writeback work initiated * @done: target wb_completion * * Initiate flush of the bdi_writeback identified by @bdi_id and @memcg_id * with the specified parameters. */ -int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr, +int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, enum wb_reason reason, struct wb_completion *done) { struct backing_dev_info *bdi; struct cgroup_subsys_state *memcg_css; struct bdi_writeback *wb; struct wb_writeback_work *work; + unsigned long dirty; int ret; /* lookup bdi and memcg */ @@ -1081,24 +1081,22 @@ int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr, } /* - * If @nr is zero, the caller is attempting to write out most of + * The caller is attempting to write out most of * the currently dirty pages. Let's take the current dirty page * count and inflate it by 25% which should be large enough to * flush out most dirty pages while avoiding getting livelocked by * concurrent dirtiers. + * + * BTW the memcg stats are flushed periodically and this is best-effort + * estimation, so some potential error is ok. */ - if (!nr) { - unsigned long filepages, headroom, dirty, writeback; - - mem_cgroup_wb_stats(wb, &filepages, &headroom, &dirty, - &writeback); - nr = dirty * 10 / 8; - } + dirty = memcg_page_state(mem_cgroup_from_css(memcg_css), NR_FILE_DIRTY); + dirty = dirty * 10 / 8; /* issue the writeback work */ work = kzalloc(sizeof(*work), GFP_NOWAIT | __GFP_NOWARN); if (work) { - work->nr_pages = nr; + work->nr_pages = dirty; work->sync_mode = WB_SYNC_NONE; work->range_cyclic = 1; work->reason = reason; diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index b4c6b613e162..7028d8e4a3d7 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -989,6 +989,16 @@ static inline void mod_memcg_state(struct mem_cgroup *memcg, local_irq_restore(flags); } +static inline unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx) +{ + long x = READ_ONCE(memcg->vmstats.state[idx]); +#ifdef CONFIG_SMP + if (x < 0) + x = 0; +#endif + return x; +} + static inline unsigned long lruvec_page_state(struct lruvec *lruvec, enum node_stat_item idx) { @@ -1444,6 +1454,11 @@ static inline void mod_memcg_state(struct mem_cgroup *memcg, { } +static inline unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx) +{ + return 0; +} + static inline unsigned long lruvec_page_state(struct lruvec *lruvec, enum node_stat_item idx) { diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 1f34ddf284dc..109e0dcd1d21 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -218,7 +218,7 @@ void wbc_attach_and_unlock_inode(struct writeback_control *wbc, void wbc_detach_inode(struct writeback_control *wbc); void wbc_account_cgroup_owner(struct writeback_control *wbc, struct page *page, size_t bytes); -int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr_pages, +int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, enum wb_reason reason, struct wb_completion *done); void cgroup_writeback_umount(void); bool cleanup_offline_cgwb(struct bdi_writeback *wb); diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 35bb5f8f9ea8..6580c2381a3e 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -631,17 +631,6 @@ void __mod_memcg_state(struct mem_cgroup *memcg, int idx, int val) cgroup_rstat_updated(memcg->css.cgroup, smp_processor_id()); } -/* idx can be of type enum memcg_stat_item or node_stat_item. */ -static unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx) -{ - long x = READ_ONCE(memcg->vmstats.state[idx]); -#ifdef CONFIG_SMP - if (x < 0) - x = 0; -#endif - return x; -} - /* idx can be of type enum memcg_stat_item or node_stat_item. */ static unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx) { @@ -4609,7 +4598,7 @@ void mem_cgroup_flush_foreign(struct bdi_writeback *wb) atomic_read(&frn->done.cnt) == 1) { frn->at = 0; trace_flush_foreign(wb, frn->bdi_id, frn->memcg_id); - cgroup_writeback_by_id(frn->bdi_id, frn->memcg_id, 0, + cgroup_writeback_by_id(frn->bdi_id, frn->memcg_id, WB_REASON_FOREIGN_FLUSH, &frn->done); }
Currently cgroup_writeback_by_id calls mem_cgroup_wb_stats() to get dirty pages for a memcg. However mem_cgroup_wb_stats() does a lot more than just get the number of dirty pages. Just directly get the number of dirty pages instead of calling mem_cgroup_wb_stats(). Also cgroup_writeback_by_id() is only called for best-effort dirty flushing, so remove the unused 'nr' parameter and no need to explicitly flush memcg stats. Signed-off-by: Shakeel Butt <shakeelb@google.com> --- fs/fs-writeback.c | 20 +++++++++----------- include/linux/memcontrol.h | 15 +++++++++++++++ include/linux/writeback.h | 2 +- mm/memcontrol.c | 13 +------------ 4 files changed, 26 insertions(+), 24 deletions(-)