diff mbox series

[v15,12/43] dept: record the latest one out of consecutive waits of the same class

Message ID 20250513100730.12664-13-byungchul@sk.com
State New
Headers show
Series DEPT(DEPendency Tracker) | expand

Commit Message

Byungchul Park May 13, 2025, 10:06 a.m. UTC 
The current code records all the waits for later use to track relation
between waits and events within each context.  However, since the same
class is handled the same way, it'd be okay to record only one on behalf
of the others if they all have the same class.

Even though it's the ideal to search the whole history buffer for that,
since it'd cost too high, alternatively, let's keep the latest one when
the same class'ed waits consecutively appear.

Signed-off-by: Byungchul Park <byungchul@sk.com>
---
 kernel/dependency/dept.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/kernel/dependency/dept.c b/kernel/dependency/dept.c
index fc1d9e8b28f9..211bafffc980 100644
--- a/kernel/dependency/dept.c
+++ b/kernel/dependency/dept.c
@@ -1485,9 +1485,28 @@  static struct dept_wait_hist *new_hist(void)
 	return wh;
 }
 
+static struct dept_wait_hist *last_hist(void)
+{
+	int pos_n = hist_pos_next();
+	struct dept_wait_hist *wh_n = hist(pos_n);
+
+	/*
+	 * This is the first try.
+	 */
+	if (!pos_n && !wh_n->wait)
+		return NULL;
+
+	return hist(pos_n + DEPT_MAX_WAIT_HIST - 1);
+}
+
 static void add_hist(struct dept_wait *w, unsigned int wg, unsigned int ctxt_id)
 {
-	struct dept_wait_hist *wh = new_hist();
+	struct dept_wait_hist *wh;
+
+	wh = last_hist();
+
+	if (!wh || wh->wait->class != w->class || wh->ctxt_id != ctxt_id)
+		wh = new_hist();
 
 	if (likely(wh->wait))
 		put_wait(wh->wait);