linux-kernel - Re: [RFC][PATCH] sched: fix GENTLE_FAIR

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]

Message-ID: <4B18E257.2080009@suse.de>
Date:	Fri, 04 Dec 2009 15:50:07 +0530
From:	Suresh Jayaraman <sjayaraman@...e.de>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC][PATCH] sched: fix GENTLE_FAIR_SLEEPERS dependency

On 12/04/2009 03:24 PM, Ingo Molnar wrote:
> 
> * Suresh Jayaraman <sjayaraman@...e.de> wrote:
> 
>> The newly introduced GENTLE_FAIR_SLEEPERS does not seem to have any
>> effect without FAIR_SLEEPERS. Fix sysctl.sched_features to reflect
>> this. Without this change, a user who sets GENTLE_FAIR_SLEEPERS
>> without FAIR_SLEEPERS would assume gentle sleeper fairness which
>> is not guaranteed.
>>
> 
> There's a lot of other dependencies between scheduler features so it's 
> possible to change it without it having an effect on the scheduler. 
> 
> sched_features is really a development/debugging facility, you have to 
> know what you are doing.

I think originally introduced as a development/debugging facility,
sched_features is slowly transforming into a viable tool for System
Administrators, by looking at the impact of turning on/off some of these
features on some workloads (especially non-desktop workloads). And I
think these benefits should be passed on to the end users perhaps in the
form of documentation.

> Might be worth adding a comment to the feature definition place itself 
> in the source - explain what it does and how it makes sense (and how it 
> doesnt).
> 

Yes it make more sense to make such changes as part of documentation
than a code enforcement. I'll try and collect some of the useful tuning
information.


Thanks,

-- 
Suresh Jayaraman
--
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/