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McKenney" , Peter Zijlstra , Phil Auld , Steven Rostedt , Thomas Gleixner , Valentin Schneider , Vlastimil Babka , linux-doc@vger.kernel.org, Bagas Sanjaya , Shuah Khan , John Ogness References: <20260427150739.bwVmmkj2@linutronix.de> Content-Language: en-US From: Waiman Long In-Reply-To: <20260427150739.bwVmmkj2@linutronix.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 On 4/27/26 11:07 AM, Sebastian Andrzej Siewior wrote: > The isolcpus= option has been marked as deprecated in 2017. Back then it > was desired for the domain sub option to be configured dynamically at > runtime instead using this boot command line which provides a static > configuration. In the meantime this option was extended by other sub > options which don't have runtime counterpart or it does not make sense > to provide one. > > The deprecated part always referred to the default `domain' sub option > but it was not obvious. Also the reasoning behind the deprecation is > sort of dubious: There is nothing wrong with a static configuration if > there is no desired to reconfigure. This is useful on systems which > have one purpose and the CPU partition configuration is not changed for > the entire lifetime. > > Remove the "Deprecated" note. Remove the part of the description which > suggest to use cpuset.sched_load_balance and instead point to the > documentation file which explains how to use cpusets to configure this > at runtime. > > Signed-off-by: Sebastian Andrzej Siewior > --- > Documentation/admin-guide/kernel-parameters.txt | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 4d0f545fb3ec5..367931fe8da56 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -2755,7 +2755,6 @@ Kernel parameters > Format: ,,, > > isolcpus= [KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance. > - [Deprecated - use cpusets instead] > Format: [flag-list,] > > Specify one or more CPUs to isolate from disturbances > @@ -2780,11 +2779,10 @@ Kernel parameters > Isolate from the general SMP balancing and scheduling > algorithms. Note that performing domain isolation this way > is irreversible: it's not possible to bring back a CPU to > - the domains once isolated through isolcpus. It's strongly > - advised to use cpusets instead to disable scheduler load > - balancing through the "cpuset.sched_load_balance" file. > - It offers a much more flexible interface where CPUs can > - move in and out of an isolated set anytime. > + the domains once isolated through this boot time > + configuration. Use cpusets for a dynamic configuration > + which can be altered at runtime. For details see > + Documentation/admin-guide/cpu-isolation.rst. > > You can move a process onto or off an "isolated" CPU via > the CPU affinity syscalls or cpuset. Acked-by: Waiman Long