From: Dave Chinner <dchinner@xxxxxxxxxx> Add a trace event to the ->writepage loop in write_cache_pages to give visibility into how the ->writepage call is changing variables within the writeback control structure. Of most interest is how wbc->nr_to_write changes from call to call, especially with filesystems that write multiple pages in ->writepage. Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> --- include/trace/events/writeback.h | 1 + mm/page-writeback.c | 1 + 2 files changed, 2 insertions(+), 0 deletions(-) diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 7867c16..6797c46 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -244,6 +244,7 @@ DEFINE_WBC_EVENT(wbc_writeback_wait); DEFINE_WBC_EVENT(wbc_balance_dirty_start); DEFINE_WBC_EVENT(wbc_balance_dirty_written); DEFINE_WBC_EVENT(wbc_balance_dirty_wait); +DEFINE_WBC_EVENT(wbc_writepage); #endif /* _TRACE_WRITEBACK_H */ diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 345a730..7ac39c5 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -921,6 +921,7 @@ continue_unlock: if (!clear_page_dirty_for_io(page)) goto continue_unlock; + trace_wbc_writepage(wbc); ret = (*writepage)(page, wbc, data); if (unlikely(ret)) { if (ret == AOP_WRITEPAGE_ACTIVATE) { -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html