linux-kernel - Re: [PATCH 2/3] sched/fair: Use HK_TYPE

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Message-ID: <Ztr7XgZd5pUWNLnY@pavilion.home>
Date: Fri, 6 Sep 2024 14:53:50 +0200
From: Frederic Weisbecker <frederic@...nel.org>
To: Waiman Long <longman@...hat.com>
Cc: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] sched/fair: Use HK_TYPE_SCHED housekeeping CPUs

Le Wed, Sep 04, 2024 at 10:54:15AM -0400, Waiman Long a écrit :
> 
> On 9/3/24 09:53, Waiman Long wrote:
> > 
> > On 9/3/24 09:12, Frederic Weisbecker wrote:
> > > Le Sun, Aug 18, 2024 at 07:45:19PM -0400, Waiman Long a écrit :
> > > > As the previous commit has enabled the setting of HK_TYPE_SCHED
> > > > housekeeping CPUs in nohz_full setup, we can now use the more aptly
> > > > named HK_TYPE_SCHED housekeeping CPUs instead of HK_TYPE_MISC.
> > > > 
> > > > Signed-off-by: Waiman Long <longman@...hat.com>
> > > Can we instead merge HK_FLAG_TICK, HK_FLAG_WQ, HK_FLAG_TIMER,
> > > HK_FLAG_RCU,
> > > HK_FLAG_MISC and HK_FLAG_KTHREAD into a single
> > > HK_FLAG_KERNEL_NOISE / HK_TYPE_KERNEL_NOISE ?
> > 
> > Sure. I am open to new name as I am not good on that.
> > HK_FLAG_KERNEL_NOISE does make sense.
> 
> I can't merge HK_FLAG_TICK just yet as it can be independently set by using
> isolcpus which can set just HK_TYPE_TICK, HK_TYPE_DOMAIN or
> HK_TYPE_MANAGED_IRQ. That is the reason why they are still separate.

Ah I think we really need to unify behaviours of isolcpus=nohz and nohz_full=

diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 5891e715f00d..9bc8fbf326cc 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -212,7 +212,8 @@ static int __init housekeeping_isolcpus_setup(char *str)
 	while (isalpha(*str)) {
 		if (!strncmp(str, "nohz,", 5)) {
 			str += 5;
-			flags |= HK_FLAG_TICK;
+			flags |= HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU |
+				 HK_FLAG_MISC | HK_FLAG_KTHREAD;
 			continue;
 		}