linux-kernel - [PATCH 1/2] psi: add support for multi level pressure stall trigger

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20220516033524.3130816-1-chenwandun@huawei.com>
Date:   Mon, 16 May 2022 11:35:23 +0800
From:   Chen Wandun <chenwandun@...wei.com>
To:     <linux-kernel@...r.kernel.org>, <hannes@...xchg.org>,
        <surenb@...gle.com>, <alexs@...nel.org>, <corbet@....net>,
        <linux-doc@...r.kernel.org>
Subject: [PATCH 1/2] psi: add support for multi level pressure stall trigger

Nowadays, psi events are triggered when stall time exceed
stall threshold, but no any different between these events.

Actually, events can be divide into multi level, each level
represent a different stall pressure, that is help to identify
pressure information more accurately.

echo "some 150000 350000 1000000" > /proc/pressure/memory would
add [150ms, 350ms) threshold for partial memory stall measured
within 1sec time window.

Signed-off-by: Chen Wandun <chenwandun@...wei.com>
---
 include/linux/psi_types.h |  3 ++-
 kernel/sched/psi.c        | 19 +++++++++++++------
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h
index c7fe7c089718..2b1393c8bf90 100644
--- a/include/linux/psi_types.h
+++ b/include/linux/psi_types.h
@@ -119,7 +119,8 @@ struct psi_trigger {
 	enum psi_states state;
 
 	/* User-spacified threshold in ns */
-	u64 threshold;
+	u64 min_threshold;
+	u64 max_threshold;
 
 	/* List node inside triggers list */
 	struct list_head node;
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 6f9533c95b0a..17dd233b533a 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -541,7 +541,7 @@ static u64 update_triggers(struct psi_group *group, u64 now)
 
 			/* Calculate growth since last update */
 			growth = window_update(&t->win, now, total[t->state]);
-			if (growth < t->threshold)
+			if (growth < t->min_threshold || growth >= t->max_threshold)
 				continue;
 
 			t->pending_event = true;
@@ -1087,15 +1087,18 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
 {
 	struct psi_trigger *t;
 	enum psi_states state;
-	u32 threshold_us;
+	u32 min_threshold_us;
+	u32 max_threshold_us;
 	u32 window_us;
 
 	if (static_branch_likely(&psi_disabled))
 		return ERR_PTR(-EOPNOTSUPP);
 
-	if (sscanf(buf, "some %u %u", &threshold_us, &window_us) == 2)
+	if (sscanf(buf, "some %u %u %u", &min_threshold_us,
+				&max_threshold_us, &window_us) == 3)
 		state = PSI_IO_SOME + res * 2;
-	else if (sscanf(buf, "full %u %u", &threshold_us, &window_us) == 2)
+	else if (sscanf(buf, "full %u %u %u", &min_threshold_us,
+				&max_threshold_us, &window_us) == 3)
 		state = PSI_IO_FULL + res * 2;
 	else
 		return ERR_PTR(-EINVAL);
@@ -1107,8 +1110,11 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
 		window_us > WINDOW_MAX_US)
 		return ERR_PTR(-EINVAL);
 
+	if (min_threshold_us >= max_threshold_us)
+		return ERR_PTR(-EINVAL);
+
 	/* Check threshold */
-	if (threshold_us == 0 || threshold_us > window_us)
+	if (max_threshold_us > window_us)
 		return ERR_PTR(-EINVAL);
 
 	t = kmalloc(sizeof(*t), GFP_KERNEL);
@@ -1117,7 +1123,8 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
 
 	t->group = group;
 	t->state = state;
-	t->threshold = threshold_us * NSEC_PER_USEC;
+	t->min_threshold = min_threshold_us * NSEC_PER_USEC;
+	t->max_threshold = max_threshold_us * NSEC_PER_USEC;
 	t->win.size = window_us * NSEC_PER_USEC;
 	window_reset(&t->win, 0, 0, 0);
 
-- 
2.25.1