linux-kernel - Re: [RFC][Patch 02/18] sched: increase SCHED_LOAD

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: <m38vuu3dms.fsf@IBM-009124035060.in.ibm.com>
Date:	Thu, 28 Apr 2011 15:24:03 +0530
From:	"Nikunj A. Dadhania" <nikunj@...ux.vnet.ibm.com>
To:	Nikhil Rao <ncrao@...gle.com>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	Paul Turner <pjt@...gle.com>, Mike Galbraith <efault@....de>,
	linux-kernel@...r.kernel.org, Nikhil Rao <ncrao@...gle.com>
Subject: Re: [RFC][Patch 02/18] sched: increase SCHED_LOAD_SCALE resolution

On Wed, 20 Apr 2011 13:51:21 -0700, Nikhil Rao <ncrao@...gle.com> wrote:
> Introduce SCHED_LOAD_RESOLUTION, which scales is added to SCHED_LOAD_SHIFT and
> increases the resolution of SCHED_LOAD_SCALE. This patch sets the value of
> SCHED_LOAD_RESOLUTION to 10, scaling up the weights for all sched entities by
> a factor of 1024. With this extra resolution, we can handle deeper cgroup
> hiearchies and the scheduler can do better shares distribution and load
> load balancing on larger systems (especially for low weight task groups).
> 
> This does not change the existing user interface, the scaled weights are only
> used internally. We do not modify prio_to_weight values or inverses, but use
> the original weights when calculating the inverse which is used to scale
> execution time delta in calc_delta_mine(). This ensures we do not lose accuracy
> when accounting time to the sched entities.
> 
> Signed-off-by: Nikhil Rao <ncrao@...gle.com>
> ---
>  include/linux/sched.h |    3 ++-
>  kernel/sched.c        |   18 ++++++++++--------
>  2 files changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 8d1ff2b..d2c3bab 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -794,7 +794,8 @@ enum cpu_idle_type {
>  /*
>   * Increase resolution of nice-level calculations:
>   */
> -#define SCHED_LOAD_SHIFT	10
> +#define SCHED_LOAD_RESOLUTION	10
> +#define SCHED_LOAD_SHIFT	(10 + SCHED_LOAD_RESOLUTION)
>  #define SCHED_LOAD_SCALE	(1L << SCHED_LOAD_SHIFT)
> 
>  /*
> diff --git a/kernel/sched.c b/kernel/sched.c
> index 50f97cc..bfee8ff 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -293,7 +293,7 @@ static DEFINE_SPINLOCK(task_group_lock);
>   *  limitation from this.)
>   */
>  #define MIN_SHARES	2
> -#define MAX_SHARES	(1UL << 18)
> +#define MAX_SHARES	(1UL << 28)
Shouldn't this change depend on SCHED_LOAD_RESOLUTION?

#define MAX_SHARES	(1UL << (18 + SCHED_LOAD_RESOLUTION))

Nikunj
--
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/