Received-SPF: pass (google.com: domain of linux-kernel+bounces-39447-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Date: Thu, 25 Jan 2024 16:06:09 -0800
From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: kuiliang Shi <seakeel@gmail.com>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>, alexs@kernel.org,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Valentin Schneider <vschneid@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/5] sched/fair: narrow the sched_use_asym_prio checking
 scenario
Message-ID: <20240126000609.GC17237@ranerica-svr.sc.intel.com>
References: <20240117085715.2614671-1-alexs@kernel.org>
 <20240117085715.2614671-5-alexs@kernel.org>
 <dd4e5498-3e21-4ac1-b65a-fd132c2a7206@linux.ibm.com>
 <e5b4eb14-c8e4-4888-b555-4b959cda8efe@gmail.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <e5b4eb14-c8e4-4888-b555-4b959cda8efe@gmail.com>
User-Agent: Mutt/1.9.4 (2018-02-28)

On Thu, Jan 25, 2024 at 05:35:32PM +0800, kuiliang Shi wrote:
> 
> 
> On 1/23/24 4:47 PM, Shrikanth Hegde wrote:
> > 
> > 
> > On 1/17/24 2:27 PM, alexs@kernel.org wrote:
> >> From: Alex Shi <alexs@kernel.org>
> >>
> >> Current function doesn't match it's comments, in fact, core_idle
> >> checking is only meaningful with non-SMT.
> >> So make the function right.
> >>
> >> Signed-off-by: Alex Shi <alexs@kernel.org>
> >> To: Valentin Schneider <vschneid@redhat.com>
> >> To: Vincent Guittot <vincent.guittot@linaro.org>
> >> To: Peter Zijlstra <peterz@infradead.org>
> >> To: Ingo Molnar <mingo@redhat.com>
> >> ---
> >>  kernel/sched/fair.c | 4 ++--
> >>  1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> >> index 96163ab69ae0..0a321f639c79 100644
> >> --- a/kernel/sched/fair.c
> >> +++ b/kernel/sched/fair.c
> >> @@ -9741,8 +9741,8 @@ group_type group_classify(unsigned int imbalance_pct,
> >>   */
> >>  static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
> >>  {
> >> -	return (!sched_smt_active()) ||
> >> -		(sd->flags & SD_SHARE_CPUCAPACITY) || is_core_idle(cpu);
> >> +	return	(sd->flags & SD_SHARE_CPUCAPACITY) ||
> >> +		(!sched_smt_active() && is_core_idle(cpu));
> >>  }
> > 
> > This seems wrong. This would always return false for higher than SMT domains 
> > if smt is active. 
> > 
> 
> yes, thanks for point out.
> 
> > Was this meant to be sched_smt_active() && is_core_idle(cpu)? 
> 
> In theory, yes, it should like this. But I have no ASYM device to test. :(

This would not work with !SMT and asym_packing.

I can test your patches on asym_packing + SMT systems if you post a new
version.