linux-kernel - Re: [PATCH 0/4] coretemp: Fix spamming of ring buffer

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Message-ID: <7e821f80b7700fcf1fb26f40bde8397f0e5e6d7e.camel@intel.com>
Date:   Wed, 29 Mar 2023 03:43:58 +0000
From:   "Zhang, Rui" <rui.zhang@...el.com>
To:     "peter.ganzhorn@...il.com" <peter.ganzhorn@...il.com>,
        "linux@...ck-us.net" <linux@...ck-us.net>
CC:     "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/4] coretemp: Fix spamming of ring buffer

Hi, Peter,

CC the list.

On Tue, 2023-03-28 at 22:37 +0200, Peter Ganzhorn wrote:
> Dear Mr. Rui,
> Dear Mr. Roeck,
> 
> please consider accepting the attached patches or
> modifying the coretemp code to stop spamming my syslog.
> I would appreciate it very much if you can accept the patches.
> 
> coretemp: Improve dynamic changes of TjMax
> After introduction of dynamic TjMax changes in commit
> c0c67f8761cec1fe36c21d85b1a5400ea7ac30cd
> my syslog gets spammed with "TjMax is ... degrees C"
> messages.
> If TjMax is subject to change at any time, it won't be
> set in tdata anymore and re-read every time from MSR.
> This causes quite a lot of dev_dbg() messages to be issued.
> 
> The following patches change the code to read TjMax
> from the MSRs into tdata->tjmax (again) but allow for a
> dynamic update at any time as well. (Patches 1 and 2)
> This way a message will only be issued after actual changes.
> Also I replaced the dev_dbg() with dev_notice (Patch 3) and
> added a additional dev_notice for the case where TjMax is
> set based on assumptions. (Patch 4)
> 
> 
> If you do not want to accept my patches, removing the
> dev_dbg() in get_tjmax() would be the most simple
> solution I guess.
> 
Please check if below patch solves your problem or not.

From 9370ee5163a85f65230b5222f1f4dece59ce078a Mon Sep 17 00:00:00 2001
From: Zhang Rui <rui.zhang@...el.com>
Date: Wed, 29 Mar 2023 11:35:18 +0800
Subject: [PATCH] hwmon: (coretemp) Avoid duplicate debug messages

Avoid duplicate dev_dbg messages when tjmax value retrieved from MSR
does not change.

Signed-off-by: Zhang Rui <rui.zhang@...el.com>
---
 drivers/hwmon/coretemp.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
index 30d77f451937..809456967b50 100644
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -267,6 +267,7 @@ static int get_tjmax(struct temp_data *tdata, struct device *dev)
 	int err;
 	u32 eax, edx;
 	u32 val;
+	static u32 tjmax;
 
 	/* use static tjmax once it is set */
 	if (tdata->tjmax)
@@ -287,7 +288,10 @@ static int get_tjmax(struct temp_data *tdata, struct device *dev)
 		 * will be used
 		 */
 		if (val) {
-			dev_dbg(dev, "TjMax is %d degrees C\n", val);
+			if (tjmax != val) {
+				dev_dbg(dev, "TjMax is %d degrees C\n", val);
+				tjmax = val;
+			}
 			return val * 1000;
 		}
 	}
-- 
2.25.1