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authorDave Chinner <dchinner@redhat.com>2010-07-07 13:24:08 +1000
committerJens Axboe <jaxboe@fusionio.com>2010-08-07 18:24:26 +0200
commit9e094383b60066996fbc3b53891324e5d2ec858d (patch)
treea3f4af7e60781f62b52dcfddd2032c3bbf933644
parent028c2dd184c097809986684f2f0627eea5529fea (diff)
downloadop-kernel-dev-9e094383b60066996fbc3b53891324e5d2ec858d.zip
op-kernel-dev-9e094383b60066996fbc3b53891324e5d2ec858d.tar.gz
writeback: Add tracing to write_cache_pages
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@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
-rw-r--r--include/trace/events/writeback.h1
-rw-r--r--mm/page-writeback.c1
2 files changed, 2 insertions, 0 deletions
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 0be26ac..bde92e0 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -148,6 +148,7 @@ 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 d556cd8..3d2111a 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -933,6 +933,7 @@ continue_unlock:
if (!clear_page_dirty_for_io(page))
goto continue_unlock;
+ trace_wbc_writepage(wbc, mapping->backing_dev_info);
ret = (*writepage)(page, wbc, data);
if (unlikely(ret)) {
if (ret == AOP_WRITEPAGE_ACTIVATE) {
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