linux-kernel - RE: [PATCH] sched: recover sched_yield task running time increase

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:	Wed, 6 Apr 2011 21:28:38 +0800
From:	"Shi, Alex" <alex.shi@...el.com>
To:	Mike Galbraith <efault@....de>
CC:	Rik van Riel <riel@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"a.p.zijlstra@...llo.nl" <a.p.zijlstra@...llo.nl>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"Chen, Tim C" <tim.c.chen@...el.com>,
	"Li, Shaohua" <shaohua.li@...el.com>
Subject: RE: [PATCH] sched: recover sched_yield task running time increase

>> > NACK
>> >
>> > This was switched off by default and under
>> > the sysctl sched_compat_yield for a reason.
>> >
>> > Reintroducing it under that sysctl option
>> > may be acceptable, but by default it would
>> > be doing the wrong thing for other workloads.
>>
>> I can implement this as sysctl option. But when I checked again the man
>> page of sched_yield. I have some concerns on this.
>>
>> ----
>>        int sched_yield(void);
>>
>> DESCRIPTION
>>        A  process  can  relinquish  the processor voluntarily without blocking by calling sched_yield().
>>        The process will then be moved to the end of the queue for its static priority and a new  process
>>        gets to run.
>> ----
>>
>> If a application calls sched_yield system call, most of time it is not
>> want to be launched again right now. so the man page said "the caller
>> process will then be moved to the _end_ of the queue..."
>
>Moving a yielding nice 0 task behind a SCHED_IDLE (or nice 19) task
>could be incredibly painful.

Good reminder! Do you have more detailed idea on this? 
--
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/