From 755f0225e8347b23a33ee6e3fb14a35310f95766 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Mon, 9 Aug 2010 17:19:18 -0700 Subject: [PATCH] vmscan: tracing: add trace event when a page is written Add a trace event for when page reclaim queues a page for IO and records whether it is synchronous or asynchronous. Excessive synchronous IO for a process can result in noticeable stalls during direct reclaim. Excessive IO from page reclaim may indicate that the system is seriously under provisioned for the amount of dirty pages that exist. Signed-off-by: Mel Gorman Acked-by: Rik van Riel Acked-by: Larry Woodman Cc: Dave Chinner Cc: Chris Mason Cc: Nick Piggin Cc: Rik van Riel Cc: Johannes Weiner Cc: Christoph Hellwig Cc: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Cc: Andrea Arcangeli Cc: Michael Rubin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/trace/events/vmscan.h | 41 +++++++++++++++++++++++++++++++++++++++++ mm/vmscan.c | 2 ++ 2 files changed, 43 insertions(+) diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h index c0552be..69789dc 100644 --- a/include/trace/events/vmscan.h +++ b/include/trace/events/vmscan.h @@ -8,6 +8,24 @@ #include #include "gfpflags.h" +#define RECLAIM_WB_ANON 0x0001u +#define RECLAIM_WB_FILE 0x0002u +#define RECLAIM_WB_SYNC 0x0004u +#define RECLAIM_WB_ASYNC 0x0008u + +#define show_reclaim_flags(flags) \ + (flags) ? __print_flags(flags, "|", \ + {RECLAIM_WB_ANON, "RECLAIM_WB_ANON"}, \ + {RECLAIM_WB_FILE, "RECLAIM_WB_FILE"}, \ + {RECLAIM_WB_SYNC, "RECLAIM_WB_SYNC"}, \ + {RECLAIM_WB_ASYNC, "RECLAIM_WB_ASYNC"} \ + ) : "RECLAIM_WB_NONE" + +#define trace_reclaim_flags(page, sync) ( \ + (page_is_file_cache(page) ? RECLAIM_WB_FILE : RECLAIM_WB_ANON) | \ + (sync == PAGEOUT_IO_SYNC ? RECLAIM_WB_SYNC : RECLAIM_WB_ASYNC) \ + ) + TRACE_EVENT(mm_vmscan_kswapd_sleep, TP_PROTO(int nid), @@ -155,6 +173,29 @@ TRACE_EVENT(mm_vmscan_lru_isolate, __entry->nr_lumpy_failed) ); +TRACE_EVENT(mm_vmscan_writepage, + + TP_PROTO(struct page *page, + int reclaim_flags), + + TP_ARGS(page, reclaim_flags), + + TP_STRUCT__entry( + __field(struct page *, page) + __field(int, reclaim_flags) + ), + + TP_fast_assign( + __entry->page = page; + __entry->reclaim_flags = reclaim_flags; + ), + + TP_printk("page=%p pfn=%lu flags=%s", + __entry->page, + page_to_pfn(__entry->page), + show_reclaim_flags(__entry->reclaim_flags)) +); + #endif /* _TRACE_VMSCAN_H */ /* This part must be outside protection */ diff --git a/mm/vmscan.c b/mm/vmscan.c index 3d006d9..b7a4e6a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -401,6 +401,8 @@ static pageout_t pageout(struct page *page, struct address_space *mapping, /* synchronous write or broken a_ops? */ ClearPageReclaim(page); } + trace_mm_vmscan_writepage(page, + trace_reclaim_flags(page, sync_writeback)); inc_zone_page_state(page, NR_VMSCAN_WRITE); return PAGE_SUCCESS; } -- 2.7.4