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From: Vlastimil Babka <vbabka@suse.cz>
To: Christoph Lameter <cl@gentwo.org>
Cc: Rustam Kovhaev <rkovhaev@gmail.com>,
	penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com,
	akpm@linux-foundation.org, corbet@lwn.net, djwong@kernel.org,
	david@fromorbit.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, linux-doc@vger.kernel.org,
	gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk,
	dvyukov@google.com
Subject: Re: [PATCH v4] slob: add size header to all allocations
Date: Mon, 22 Nov 2021 12:49:35 +0100	[thread overview]
Message-ID: <56c0671c-6db2-05ac-66a0-6f24101e6c5a@suse.cz> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2111221239050.205511@gentwo.de>

On 11/22/21 12:40, Christoph Lameter wrote:
> On Mon, 22 Nov 2021, Vlastimil Babka wrote:
> 
>> It's no problem to have the real beginning of the object aligned, and the
>> prepended header not. The code already does that before this patch for the
>> kmalloc power-of-two alignments, where e.g. the object can be aligned to 256
>> bytes, but the prepended header to a smaller ARCH_KMALLOC_MINALIGN /
>> ARCH_SLAB_MINALIGN.
> 
> Ok but then the first object in a page may still have those issues.

Hmm, that's right. I guess we should also distinguish ARCH_KMALLOC_MINALIGN
for kmalloc paths, and ARCH_SLAB_MINALIGN for kmem_cache_alloc paths. Seems
the latter is generally smaller, thus some holes left by kmalloc allocations
could be filled later by kmem_cache_alloc allocations.

> 
>> > I dont know but it seems that making slob that sophisticated is counter
>> > productive. Remove SLOB?
>>
>> I wouldn't mind, but somebody might :)
> 
> Well run a space efficiency analysis after this patch. If the memory used
> is larger than SLUB (with the configuration for minimal data footprint)
> then there is no reason for SLOB to continue.

Makes sense.

  reply	other threads:[~2021-11-22 11:49 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-29 21:23 [PATCH] xfs: use kmem_cache_free() for kmem_cache objects Rustam Kovhaev
2021-09-30  4:42 ` Dave Chinner
2021-09-30  8:13   ` Vlastimil Babka
2021-09-30 18:48     ` Rustam Kovhaev
2021-09-30 21:10       ` Vlastimil Babka
2021-10-01  0:32         ` Rustam Kovhaev
2021-10-04  1:07           ` David Rientjes
2021-10-04  1:07             ` David Rientjes
2021-10-12 20:43             ` Darrick J. Wong
2021-10-12 20:43               ` Darrick J. Wong
2021-10-12 21:32                 ` Vlastimil Babka
2021-10-12 23:22                   ` Darrick J. Wong
2021-10-13  7:38                     ` Vlastimil Babka
2021-10-13 16:56                       ` Rustam Kovhaev
2021-10-15  0:57                         ` Darrick J. Wong
2021-10-18  3:38                           ` [PATCH] slob: add size header to all allocations Rustam Kovhaev
2021-10-18  9:22                             ` Vlastimil Babka
2021-10-19  1:22                               ` Rustam Kovhaev
2021-10-20 11:46                             ` Hyeonggon Yoo
2021-10-21 17:36                               ` Vlastimil Babka
2021-10-23  6:41                                 ` [PATCH v2] " Rustam Kovhaev
2021-10-25  9:36                                   ` Vlastimil Babka
2021-10-25 21:49                                     ` Rustam Kovhaev
2021-10-29  3:05                                     ` [PATCH v3] " Rustam Kovhaev
2021-11-16 11:26                                       ` Vlastimil Babka
2021-11-16 23:19                                         ` Rustam Kovhaev
2021-11-22  1:30                                         ` [PATCH v4] " Rustam Kovhaev
2021-11-22  9:22                                           ` Christoph Lameter
2021-11-22  9:40                                             ` Vlastimil Babka
2021-11-22 10:36                                               ` Christoph Lameter
2021-11-22 10:45                                                 ` Vlastimil Babka
2021-11-22 11:40                                                   ` Christoph Lameter
2021-11-22 11:49                                                     ` Vlastimil Babka [this message]
2021-11-23 10:18                                                   ` David Laight
2021-11-30  7:00                                                     ` Rustam Kovhaev
2021-11-30  9:23                                                       ` David Laight
2021-11-30  9:41                                                       ` Christoph Lameter
2021-11-30 14:55                                                     ` Vlastimil Babka
2021-11-30 15:21                                                       ` David Laight
2021-11-30 15:39                                                         ` Vlastimil Babka
2021-11-30 15:26                                                       ` Christoph Lameter
2021-10-24 10:43                                 ` [PATCH] " Hyeonggon Yoo
2021-10-25  8:19                                   ` Vlastimil Babka

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