linux-kernel - Re: [PATCH 0/2] cpusets,isolcpus: resolve conflict between cpusets and isolcpus

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 24 Feb 2015 09:13:04 -0500
From:	Rik van Riel <riel@...hat.com>
To:	Mike Galbraith <umgwanakikbuti@...il.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] cpusets,isolcpus: resolve conflict between cpusets
 and isolcpus

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 02/23/2015 09:18 PM, Mike Galbraith wrote:
> On Mon, 2015-02-23 at 16:45 -0500, riel@...hat.com wrote:
>> Ensure that cpus specified with the isolcpus= boot commandline 
>> option stay outside of the load balancing in the kernel
>> scheduler.
>> 
>> Operations like load balancing can introduce unwanted latencies, 
>> which is exactly what the isolcpus= commandline is there to
>> prevent.
>> 
>> Previously, simply creating a new cpuset, without even touching
>> the cpuset.cpus field inside the new cpuset, would undo the
>> effects of isolcpus=, by creating a scheduler domain spanning the
>> whole system, and setting up load balancing inside that domain.
>> The cpuset root cpuset.cpus file is read-only, so there was not
>> even a way to undo that effect.
>> 
>> This does not impact the majority of cpusets users, since
>> isolcpus= is a fairly specialized feature used for realtime
>> purposes.
> 
> 3/3: nohz_full cpus become part of that unified isolated map?

There may be use cases where users want nohz_full, but still
want the scheduler to automatically load balance the CPU.

I am not sure whether we want nohz_full and isolcpus to always
overlap 100%.

On the other hand, any CPU that is isolated with isolcpus=
probably wants nohz_full...

- -- 
All rights reversed
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1

iQEcBAEBAgAGBQJU7IbwAAoJEM553pKExN6DxpAIAIt3Wp1fYhyTiceCZPZj/75y
aNdpa1tsdyZmC3UoqHlWPajhU9kz3LV88gkDuRVLkBSIbAdc+Krpj0QwU80SBpn8
MIRkzlDE5pHwqgpNEmY0dTI8OP/BWH6SzgkbAqACTeffR8glz49ELFL2IK9hSl4P
2j5gOc1sgBD24cpqComw0qpIJwhRfDTr270zHPzEcqwESYLD57Z6AZxLuz8UjDnD
vgvmz5+zCeVKfPWfFSCUHGDZ56PuQAvQk0olAVp5pd6wwGoPyAMNJm12RgE2ru0M
8y/xyHAhbtzdV7XsdfBWWe6F4jmodvjhKKtqRdwGzQSGkJzxGjdlFBeSkOkeBsk=
=4dML
-----END PGP SIGNATURE-----
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/