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Date: Mon, 16 Apr 2018 10:45:48 -0500 (CDT)
From: Christopher Lameter <cl@linux.com>
Subject: Re: slab: introduce the flag SLAB_MINIMIZE_WASTE
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To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>, Vlastimil Babka <vbabka@suse.cz>, Matthew Wilcox <willy@infradead.org>, Pekka Enberg <penberg@kernel.org>, linux-mm@kvack.org, dm-devel@redhat.com, David Rientjes <rientjes@google.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Andrew Morton <akpm@linux-foundation.org>

On Mon, 16 Apr 2018, Mikulas Patocka wrote:

> >
> > Or an increase in slab_max_order
>
> But that will increase it for all slabs (often senselessly - i.e.
> kmalloc-4096 would have order 4MB).

4MB? Nope.... That is a power of two slab so no wasted space even with
order 0.

Its not a senseless increase. The more objects you fit into a slab page
the higher the performance of the allocator.


> I need to increase it just for dm-bufio slabs.

If you do this then others will want the same...

From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christopher Lameter <cl@linux.com>
Subject: Re: slab: introduce the flag SLAB_MINIMIZE_WASTE
Date: Mon, 16 Apr 2018 10:45:48 -0500 (CDT)
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On Mon, 16 Apr 2018, Mikulas Patocka wrote:

> >
> > Or an increase in slab_max_order
>
> But that will increase it for all slabs (often senselessly - i.e.
> kmalloc-4096 would have order 4MB).

4MB? Nope.... That is a power of two slab so no wasted space even with
order 0.

Its not a senseless increase. The more objects you fit into a slab page
the higher the performance of the allocator.


> I need to increase it just for dm-bufio slabs.

If you do this then others will want the same...