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From: Andi Kleen <andi@firstfloor.org>
To: Michal Hocko <mhocko@suse.cz>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Expose sysctls for enabling slab/file_cache interleaving
Date: Tue, 19 Nov 2013 13:49:28 -0800	[thread overview]
Message-ID: <87y54kvz87.fsf@tassilo.jf.intel.com> (raw)
In-Reply-To: <20131119212123.GA9339@dhcp22.suse.cz> (Michal Hocko's message of "Tue, 19 Nov 2013 22:21:23 +0100")

Michal Hocko <mhocko@suse.cz> writes:
>
> Another option would be to use sysctl values for the top cpuset as a
> default. But then why not just do it manually without sysctl?

I want to provide an alternative to having to use cpusets to use this,
that is actually usable for normal people.

Also this is really a global setting in my mind.

> If you create a cpuset and explicitly disable spreading then you would
> be quite surprised that your process gets pages from all nodes, no?

If I enable it globally using a sysctl I would be quite surprised 
if some cpuset can override it.

That argument is equally valid :-)

The user configured an inconsistent configuration, and the kernel
has to make a decision somehow.

In the end it is arbitary, but not having to check the cpuset
here is a lot cheaper, so I prefer the "sysctl has priority" 
option.

Could EINVAL the cpuset setting when the sysctl is set
though (but it's difficult to do the other way round).

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only

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WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <andi@firstfloor.org>
To: Michal Hocko <mhocko@suse.cz>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Expose sysctls for enabling slab/file_cache interleaving
Date: Tue, 19 Nov 2013 13:49:28 -0800	[thread overview]
Message-ID: <87y54kvz87.fsf@tassilo.jf.intel.com> (raw)
In-Reply-To: <20131119212123.GA9339@dhcp22.suse.cz> (Michal Hocko's message of "Tue, 19 Nov 2013 22:21:23 +0100")

Michal Hocko <mhocko@suse.cz> writes:
>
> Another option would be to use sysctl values for the top cpuset as a
> default. But then why not just do it manually without sysctl?

I want to provide an alternative to having to use cpusets to use this,
that is actually usable for normal people.

Also this is really a global setting in my mind.

> If you create a cpuset and explicitly disable spreading then you would
> be quite surprised that your process gets pages from all nodes, no?

If I enable it globally using a sysctl I would be quite surprised 
if some cpuset can override it.

That argument is equally valid :-)

The user configured an inconsistent configuration, and the kernel
has to make a decision somehow.

In the end it is arbitary, but not having to check the cpuset
here is a lot cheaper, so I prefer the "sysctl has priority" 
option.

Could EINVAL the cpuset setting when the sysctl is set
though (but it's difficult to do the other way round).

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only

  reply	other threads:[~2013-11-19 21:49 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-19  0:50 [PATCH] Expose sysctls for enabling slab/file_cache interleaving Andi Kleen
2013-11-19  0:50 ` Andi Kleen
2013-11-19 10:42 ` Michal Hocko
2013-11-19 10:42   ` Michal Hocko
2013-11-19 18:42   ` Andi Kleen
2013-11-19 18:42     ` Andi Kleen
2013-11-19 19:11     ` Michal Hocko
2013-11-19 19:11       ` Michal Hocko
2013-11-19 20:13       ` Andi Kleen
2013-11-19 20:13         ` Andi Kleen
2013-11-19 21:21         ` Michal Hocko
2013-11-19 21:21           ` Michal Hocko
2013-11-19 21:49           ` Andi Kleen [this message]
2013-11-19 21:49             ` Andi Kleen
2013-11-20  5:49             ` KOSAKI Motohiro
2013-11-20  5:49               ` KOSAKI Motohiro

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