linux-kernel - Re: [PATCH v4 1/2] sched/topology: improve topology_span

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Message-ID: <20250611060607.GM10669@unreal>
Date: Wed, 11 Jun 2025 09:06:07 +0300
From: Leon Romanovsky <leon@...nel.org>
To: Steve Wahl <steve.wahl@....com>
Cc: K Prateek Nayak <kprateek.nayak@....com>,
	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,
	Vishal Chourasia <vishalc@...ux.ibm.com>,
	samir <samir@...ux.ibm.com>,
	Naman Jain <namjain@...ux.microsoft.com>,
	Saurabh Singh Sengar <ssengar@...ux.microsoft.com>,
	srivatsa@...il.mit.edu, Michael Kelley <mhklinux@...look.com>,
	Russ Anderson <rja@....com>, Dimitri Sivanich <sivanich@....com>
Subject: Re: [PATCH v4 1/2] sched/topology: improve topology_span_sane speed

On Tue, Jun 10, 2025 at 02:39:54PM -0500, Steve Wahl wrote:
> On Tue, Jun 10, 2025 at 04:09:52PM +0300, Leon Romanovsky wrote:
> > 
> > 
> > On Tue, Jun 10, 2025, at 15:36, Leon Romanovsky wrote:
> > > On Tue, Jun 10, 2025 at 05:03:14PM +0530, K Prateek Nayak wrote:
> > >> Hello Leon,
> > >> 
> > >> On 6/10/2025 4:37 PM, Leon Romanovsky wrote:
> > >> 
> > >> [..snip..]
> > >> 
> > >> > > +	if (WARN_ON(!topology_span_sane(cpu_map)))
> > >> > > +		goto error;
> > >> > 
> > >> > Hi,

<...>

> > [    0.032233] [mem 0xc0000000-0xfed1bfff] available for PCI devices
> > [    0.032237] Booting paravirtualized kernel on KVM
> > [    0.032238] clocksource: refined-jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645519600211568 ns
> > [    0.036921] setup_percpu: NR_CPUS:512 nr_cpumask_bits:10 nr_cpu_ids:10 nr_node_ids:5
> > [    0.038074] percpu: Embedded 53 pages/cpu s177240 r8192 d31656 u1048576
> > [    0.038108] Kernel command line: BOOT_IMAGE=(hd0,msdos1)/boot/vmlinuz-6.16.0-rc1_for_upstream_min_debug_2025_06_09_14_44 root=UUID=49650207-5673-41e8-9f3b-5572de97a271 ro selinux=0 kasan_multi_shot net.ifnames=0 biosdevname=0 console=tty0 console=ttyS1,115200 audit=0 systemd.unified_cgroup_hierarchy=0 sched_verbose
> > [    0.038222] Unknown kernel command line parameters "kasan_multi_shot BOOT_IMAGE=(hd0,msdos1)/boot/vmlinuz-6.16.0-rc1_for_upstream_min_debug_2025_06_09_14_44 selinux=0 biosdevname=0 audit=0", will be passed to user space.

<...>

> 
> I don't think that's the full dmesg output, maybe a console capture
> with reduced levels?  I'm not finding the output of sched_domain_debug() and
> sched_domain_debug_one() here.

It is not reduced, but standard debug level log, where KERN_DEBUG prints
aren't printed.

I don't know why sched_verbose is implemented how it is implemented,
but all these KERN_DEBUG prints in sched_domain_debug_one() are not controlled
through sched_verbose.

Thanks

> 
> Thanks,
> 
> Steve Wahl
> 
> > >
> > > Thanks
> > >
> > >> 
> > >> -- 
> > >> Thanks and Regards,
> > >> Prateek
> > >> 
> > >> > 
> > >> > Thanks
> > >> > 
> > >> > > +
> > >> > >   	/* Build the groups for the domains */
> > >> > >   	for_each_cpu(i, cpu_map) {
> > >> > >   		for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
> > >> > > -- 
> > >> > > 2.26.2
> > >> > > 
> > >>
> 
> -- 
> Steve Wahl, Hewlett Packard Enterprise