Received-SPF: pass (google.com: domain of linux-kernel+bounces-71509-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Date: Mon, 19 Feb 2024 22:37:01 +0800
From: Feng Tang <feng.tang@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
CC: John Stultz <jstultz@google.com>, Stephen Boyd <sboyd@kernel.org>,
	<paulmck@kernel.org>, Waiman Long <longman@redhat.com>, Peter Zijlstra
	<peterz@infradead.org>, <linux-kernel@vger.kernel.org>, Jin Wang
	<jin1.wang@intel.com>
Subject: Re: [PATCH v3] clocksource: Scale the max retry number of watchdog
 read according to CPU numbers
Message-ID: <ZdNnjdNTjtvpbGH0@feng-clx.sh.intel.com>
References: <20240129134505.961208-1-feng.tang@intel.com>
 <87msrwadvu.ffs@tglx>
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <87msrwadvu.ffs@tglx>
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?tRE0qgXyisMSGm1Uc6+VV3gW5hrUXWbEXyRCKMdFvVBVySZSFSleZL1OI+7M?=
 =?us-ascii?Q?+9dR3yE4DzdAoaS0dnRZEVD9wpIWHUFrGHBy7jXfKQWY+xdveqKqRqsbQlmU?=
 =?us-ascii?Q?kfWH8aiNg52PhciEGMfrsIrN8zLxQUKE6bi2xJ2qzNauJ43AD4f4N7Zm9cql?=
 =?us-ascii?Q?/HUOR0LVj0sBvC2AWVKgLFibX+WAjiQ+MPPTEhltE7oJ2TtUzgDtBDdjjsy6?=
 =?us-ascii?Q?8CsEk8igUYpTKsomouZE1Ukmfiilivjf40RIoY0RTL99AVLhTbIM1noV90iM?=
 =?us-ascii?Q?v7ZtwiOThQ5LxH2nj/lJVSsJWVW5f/sfIpZi+1A1LNLLKno5WISNf/goyllr?=
 =?us-ascii?Q?CSKXk62wk9w4G4GT6NwHQvjXeQueR0gbbTckyN2StGjEGgMUzjga29RbjNB5?=
 =?us-ascii?Q?sTo+USzs76pSUoG5ClmZ6KCh2d7e3RMKdyJYTt2j/8n66SBvtEE87TZvtAmQ?=
 =?us-ascii?Q?vdqRUwAgMiq8wxx61BkVFLaY2xbQhMlNopmPuYfDdo4TZvUgYox/3P61Uw75?=
 =?us-ascii?Q?CkqvbZCsXsBCiab9r5f/hR1Z7J2nldZ+vAbVzlnPR6aRlc4Wfyh/VyQm0h6G?=
 =?us-ascii?Q?BngQXbeeK1VkcQHzKZXQaBlQzN68mHWKHHN/VW41C3h/SgReQyUTXm1adZDR?=
 =?us-ascii?Q?UQKSI1E4wFYUI6YrMmZ0m5wbC7cPZHOAHwvAt/gpNRACR/9MOk9YHNsPqCBH?=
 =?us-ascii?Q?K9r5v26LjHys5nWAi/KghzMe7ESCsmRmkXKl0WQ4ZdmPdfdy+TpWKDbluNWG?=
 =?us-ascii?Q?jca51hf5yL5Yxgtc7ZSy86fyu9FCuvlqaVeNCpghd+9fZtve09v1+itXR1l8?=
 =?us-ascii?Q?fUtlw2YkUxqkUsm8VeqMMd3/esdiwO1NyxudzylFhYeeIFgJX14C7ubnbtqy?=
 =?us-ascii?Q?frwlEeJYZwScbqxE/k0usCmh9cOd1Z7Nr6XHERr7hqv755vvaqM1w323YxEU?=
 =?us-ascii?Q?LT1qDtODHSdIhkA8V6FiiYa76/wGsV8423BP//viebzUtWta7YDjs2xaLd4G?=
 =?us-ascii?Q?4NhInmZPjBctTwR0JwViG7SWYDIeimraK8VwCwnDoO7H26zSfu6biUGJRjwu?=
 =?us-ascii?Q?Q4RKDLCy/3Fju2kZPZzlGbqn+bl+QftP4B3zj89nzKXA4FcHY95dtumt2lrC?=
 =?us-ascii?Q?hBTll0CUuA6MZxzUZsoLbGIQOX9Tqr4sE+eoXnLd7+hucdASlfhoQqcluCXl?=
 =?us-ascii?Q?370lZJ+xiCHwM6AI4jgF7ZOJ4pL4lzpB/bijEV2vTpRq9BjhaaEPm+aErbVN?=
 =?us-ascii?Q?pDYuAFs+ADY1P9ol9dXGu3QXP3hQ8RGxTUKrfwydfdh7QkTwazSJSLRssIJv?=
 =?us-ascii?Q?pzKGtkFSdTx+WX0TOEfiJdZe9JgOHsfiRvL5wz8kZsCOMP9DVYcgTBnu6QFR?=
 =?us-ascii?Q?J8lOW8Sz4JB7uYuTK+PqdmpNhCds3Nrz3nE41805lLXMn9dVQ1kp2PyHtIva?=
 =?us-ascii?Q?ETFiarnxG7Nl2RTu6eLkOkC/h5SEhaoNBrAtdHdtRSWs2aJPQYFmwjvfLZN+?=
 =?us-ascii?Q?0idR9D2DlCvgWneNgY4+2dSv71tZTBJoE+v9YmlAwz1K9uY1yIi0vbOKnahY?=
 =?us-ascii?Q?XpLhRi8ZFsKx/KaLSN+aegTA37Pb73HxPHKfqVLz?=
X-MS-Exchange-CrossTenant-Network-Message-Id: 804d5def-c0e9-4770-057a-08dc315a3721
X-MS-Exchange-CrossTenant-AuthSource: MN0PR11MB6304.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Feb 2024 14:51:12.2456
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: lteaOfpBcvkvf2QWxyVIw+4ZS20lI0r31qg1p2GcZUuGQWQhXxz/gi4eqYYqiUa8lwBM5hiHTBEyr3of6vbazQ==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR11MB7801
X-OriginatorOrg: intel.com

Hi Thomas,

On Mon, Feb 19, 2024 at 12:32:05PM +0100, Thomas Gleixner wrote:
> On Mon, Jan 29 2024 at 21:45, Feng Tang wrote:
> > +static inline long clocksource_max_watchdog_read_retries(void)
> > +{
> > +	long max_retries = max_cswd_read_retries;
> > +
> > +	if (max_cswd_read_retries <= 0) {
> > +		/* santity check for user input value */
> > +		if (max_cswd_read_retries != -1)
> > +			pr_warn_once("max_cswd_read_retries was set with an invalid number: %ld\n",
> > +				max_cswd_read_retries);
> > +
> > +		max_retries = ilog2(num_online_cpus()) + 1;
> 
> I'm getting tired of these knobs and the horrors behind them. Why not
> simply doing the obvious:
> 
>        retries = ilog2(num_online_cpus()) + 1;
> 
> and remove the knob alltogether?

Thanks for the suggestion! Yes, this makes sense to me. IIUC, the
'max_cswd_read_retries' was introduced mainly to cover different
platforms' requirement, which could now be covered by the new
self-adaptive number.

If there is no concern from other developers, I will send a new
version in this direction.

Thanks,
Feng

> 
> Thanks,
> 
>         tglx