linux-kernel - [PATCH] PM / suspend: measure the time of filesystem syncing

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: <20190203052007.27392-1-harry.pan@intel.com>
Date:   Sun,  3 Feb 2019 13:20:07 +0800
From:   Harry Pan <harry.pan@...el.com>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     gs0622@...il.com, Harry Pan <harry.pan@...el.com>,
        rjw@...ysocki.net, pavel@....cz, len.brown@...el.com,
        linux-pm@...r.kernel.org
Subject: [PATCH] PM / suspend: measure the time of filesystem syncing

This patch gives the reader an intuitive metric of the time cost by
the kernel issuing a filesystem sync during suspend; although developer
can guess by the timestamp of next log or enable the ftrace power event
for manual calculation, this manner is easier to read and benefits the
automatic script.

Signed-off-by: Harry Pan <harry.pan@...el.com>
---
 kernel/power/suspend.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 0bd595a0b610..f3b7c64f2242 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -550,6 +550,8 @@ static void suspend_finish(void)
 static int enter_state(suspend_state_t state)
 {
 	int error;
+	ktime_t start, end, elapsed;
+	unsigned int elapsed_msecs;
 
 	trace_suspend_resume(TPS("suspend_enter"), state, true);
 	if (state == PM_SUSPEND_TO_IDLE) {
@@ -570,9 +572,14 @@ static int enter_state(suspend_state_t state)
 
 #ifndef CONFIG_SUSPEND_SKIP_SYNC
 	trace_suspend_resume(TPS("sync_filesystems"), 0, true);
+	start = ktime_get_boottime();
 	pr_info("Syncing filesystems ... ");
 	ksys_sync();
-	pr_cont("done.\n");
+	end = ktime_get_boottime();
+	elapsed = ktime_sub(end, start);
+	elapsed_msecs = ktime_to_ms(elapsed);
+	pr_cont("(elapsed %d.%03d seconds) done.\n", elapsed_msecs / 1000,
+		elapsed_msecs % 1000);
 	trace_suspend_resume(TPS("sync_filesystems"), 0, false);
 #endif
 
-- 
2.18.1