linux-kernel - Re: [PATCH 4/5] mm/slub: Limit min

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Date:   Thu, 24 Feb 2022 13:52:00 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Hyeonggon Yoo <42.hyeyoo@...il.com>,
        David Rientjes <rientjes@...gle.com>
Cc:     linux-mm@...ck.org, Roman Gushchin <guro@...com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, Joonsoo Kim <iamjoonsoo.kim@....com>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>
Subject: Re: [PATCH 4/5] mm/slub: Limit min_partial only in cache creation

On 2/23/22 04:37, Hyeonggon Yoo wrote:
> On Tue, Feb 22, 2022 at 03:48:16PM -0800, David Rientjes wrote:
>> On Mon, 21 Feb 2022, Hyeonggon Yoo wrote:
>> 
>> > SLUB sets number of minimum partial slabs for node (min_partial) using
>> > set_min_partial(). SLUB holds at least min_partial slabs even if they're empty
>> > to avoid excessive use of page allocator.
>> > 
>> > set_min_partial() limits value of min_partial between MIN_PARTIAL and
>> > MAX_PARTIAL. As set_min_partial() can be called by min_partial_store()
>> > too, Only limit value of min_partial in kmem_cache_open() so that it
>> > can be changed to value that a user wants.
>> > 
>> > Signed-off-by: Hyeonggon Yoo <42.hyeyoo@...il.com>
>> 
>> I think this makes sense and there is no reason to limit the bounds that 
>> may be set at runtime with undocumented behavior.

Right.

> Thank you for comment.
> 
>> 
>> However, since set_min_partial() is only setting the value in the 
>> kmem_cache, could we remove the helper function entirely and fold it into 
>> its two callers?
> 
> Right. We don't need to separate this as function. I'll update this
> in next version. Thanks!

Agreed, thanks!