linux-kernel - Re: [PATCH] slub: try to get cpu partial slab even if we get enough objects for cpu freelist

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Message-ID: <000001393515ab5f-b518fa1e-a5e1-4849-b711-c2ebbdfd65a1-000000@email.amazonses.com>
Date:	Fri, 17 Aug 2012 14:56:16 +0000
From:	Christoph Lameter <cl@...ux.com>
To:	JoonSoo Kim <js1304@...il.com>
cc:	Pekka Enberg <penberg@...nel.org>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH] slub: try to get cpu partial slab even if we get enough
 objects for cpu freelist

On Fri, 17 Aug 2012, JoonSoo Kim wrote:

> In case of !object (available =  page->objects - page->inuse;),
> "available" means the number of objects in cpu slab.

Right because we do not have allocated any cpu partial slabs yet.

> In this time, we don't have any cpu partial slab, so "available" imply
> the number of objects available to the cpu without locking.
> This is what we want.
>
>
> But, see another "available" (available = put_cpu_partial(s, page, 0);).
>
> This "available" doesn't include the number of objects in cpu slab.

Ok. Now I see.

> Therefore, I think a minor fix is needed for consistency.
> Isn't it reasonable?

Yup it is. Let me look over your patch again.

Ok so use meaningful names for the variables to clarify the issue.

cpu_objects and partial_objects or so?

Then the check would be as you proposed in the last message

if (cpu_objects + partial_objects < s->cpu_partial ...


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