From 3a8e9ac89e6a5106cfb6b85d4c9cf9bfa3519bc7 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 29 Aug 2019 15:47:19 -0700 Subject: [PATCH] writeback: add tracepoints for cgroup foreign writebacks cgroup foreign inode handling has quite a bit of heuristics and internal states which sometimes makes it difficult to understand what's going on. Add tracepoints to improve visibility. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- fs/fs-writeback.c | 5 ++ include/trace/events/writeback.h | 123 +++++++++++++++++++++++++++++++ mm/memcontrol.c | 5 ++ 3 files changed, 133 insertions(+) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 658dc16c9e6d..8aaa7eec7b74 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -389,6 +389,8 @@ static void inode_switch_wbs_work_fn(struct work_struct *work) if (unlikely(inode->i_state & I_FREEING)) goto skip_switch; + trace_inode_switch_wbs(inode, old_wb, new_wb); + /* * Count and transfer stats. Note that PAGECACHE_TAG_DIRTY points * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to @@ -673,6 +675,9 @@ void wbc_detach_inode(struct writeback_control *wbc) if (wbc->wb_id != max_id) history |= (1U << slots) - 1; + if (history) + trace_inode_foreign_history(inode, wbc, history); + /* * Switch if the current wb isn't the consistent winner. * If there are multiple closely competing dirtiers, the diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index aa7f3aeac740..3dc9fb9e7c78 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -176,6 +176,129 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w #endif /* CONFIG_CGROUP_WRITEBACK */ #endif /* CREATE_TRACE_POINTS */ +#ifdef CONFIG_CGROUP_WRITEBACK +TRACE_EVENT(inode_foreign_history, + + TP_PROTO(struct inode *inode, struct writeback_control *wbc, + unsigned int history), + + TP_ARGS(inode, wbc, history), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(unsigned long, ino) + __field(unsigned int, cgroup_ino) + __field(unsigned int, history) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(inode_to_bdi(inode)->dev), 32); + __entry->ino = inode->i_ino; + __entry->cgroup_ino = __trace_wbc_assign_cgroup(wbc); + __entry->history = history; + ), + + TP_printk("bdi %s: ino=%lu cgroup_ino=%u history=0x%x", + __entry->name, + __entry->ino, + __entry->cgroup_ino, + __entry->history + ) +); + +TRACE_EVENT(inode_switch_wbs, + + TP_PROTO(struct inode *inode, struct bdi_writeback *old_wb, + struct bdi_writeback *new_wb), + + TP_ARGS(inode, old_wb, new_wb), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(unsigned long, ino) + __field(unsigned int, old_cgroup_ino) + __field(unsigned int, new_cgroup_ino) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(old_wb->bdi->dev), 32); + __entry->ino = inode->i_ino; + __entry->old_cgroup_ino = __trace_wb_assign_cgroup(old_wb); + __entry->new_cgroup_ino = __trace_wb_assign_cgroup(new_wb); + ), + + TP_printk("bdi %s: ino=%lu old_cgroup_ino=%u new_cgroup_ino=%u", + __entry->name, + __entry->ino, + __entry->old_cgroup_ino, + __entry->new_cgroup_ino + ) +); + +TRACE_EVENT(track_foreign_dirty, + + TP_PROTO(struct page *page, struct bdi_writeback *wb), + + TP_ARGS(page, wb), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(u64, bdi_id) + __field(unsigned long, ino) + __field(unsigned int, memcg_id) + __field(unsigned int, cgroup_ino) + __field(unsigned int, page_cgroup_ino) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(wb->bdi->dev), 32); + __entry->bdi_id = wb->bdi->id; + __entry->ino = page->mapping->host->i_ino; + __entry->memcg_id = wb->memcg_css->id; + __entry->cgroup_ino = __trace_wb_assign_cgroup(wb); + __entry->page_cgroup_ino = page->mem_cgroup->css.cgroup->kn->id.ino; + ), + + TP_printk("bdi %s[%llu]: ino=%lu memcg_id=%u cgroup_ino=%u page_cgroup_ino=%u", + __entry->name, + __entry->bdi_id, + __entry->ino, + __entry->memcg_id, + __entry->cgroup_ino, + __entry->page_cgroup_ino + ) +); + +TRACE_EVENT(flush_foreign, + + TP_PROTO(struct bdi_writeback *wb, unsigned int frn_bdi_id, + unsigned int frn_memcg_id), + + TP_ARGS(wb, frn_bdi_id, frn_memcg_id), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(unsigned int, cgroup_ino) + __field(unsigned int, frn_bdi_id) + __field(unsigned int, frn_memcg_id) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(wb->bdi->dev), 32); + __entry->cgroup_ino = __trace_wb_assign_cgroup(wb); + __entry->frn_bdi_id = frn_bdi_id; + __entry->frn_memcg_id = frn_memcg_id; + ), + + TP_printk("bdi %s: cgroup_ino=%u frn_bdi_id=%u frn_memcg_id=%u", + __entry->name, + __entry->cgroup_ino, + __entry->frn_bdi_id, + __entry->frn_memcg_id + ) +); +#endif + DECLARE_EVENT_CLASS(writeback_write_inode_template, TP_PROTO(struct inode *inode, struct writeback_control *wbc), diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 89b65f5ca634..4390994e8be9 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4066,6 +4066,8 @@ static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css, #ifdef CONFIG_CGROUP_WRITEBACK +#include + static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp) { return wb_domain_init(&memcg->cgwb_domain, gfp); @@ -4203,6 +4205,8 @@ void mem_cgroup_track_foreign_dirty_slowpath(struct page *page, int oldest = -1; int i; + trace_track_foreign_dirty(page, wb); + /* * Pick the slot to use. If there is already a slot for @wb, keep * using it. If not replace the oldest one which isn't being @@ -4263,6 +4267,7 @@ void mem_cgroup_flush_foreign(struct bdi_writeback *wb) if (time_after64(frn->at, now - intv) && 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, WB_REASON_FOREIGN_FLUSH, &frn->done); -- 2.39.5