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From: Hyeonggon Yoo <42.hyeyoo@gmail.com>
To: Rustam Kovhaev <rkovhaev@gmail.com>
Cc: vbabka@suse.cz, cl@linux.com, penberg@kernel.org,
	rientjes@google.com, iamjoonsoo.kim@lge.com,
	akpm@linux-foundation.org, djwong@kernel.org,
	david@fromorbit.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, gregkh@linuxfoundation.org,
	viro@zeniv.linux.org.uk, dvyukov@google.com
Subject: Re: [PATCH] slob: add size header to all allocations
Date: Wed, 20 Oct 2021 11:46:38 +0000	[thread overview]
Message-ID: <20211020114638.GA378758@kvm.asia-northeast3-a.c.our-ratio-313919.internal> (raw)
In-Reply-To: <20211018033841.3027515-1-rkovhaev@gmail.com>

On Sun, Oct 17, 2021 at 08:38:41PM -0700, Rustam Kovhaev wrote:
> Let's prepend all  allocations of (PAGE_SIZE - align_offset) and less
> with the size header. This way kmem_cache_alloc() memory can be freed
> with kfree() and the other way around, as long as they are less than
> (PAGE_SIZE - align_offset).

Hello Rustam, I measured its impact on memory usage on
tiny kernel configuration as SLOB is used in very small machine.

on x86 32 bit + tinyconfig:
    Before:
    Slab:                668 kB

    After:
    Slab:                688~692 kB

it adds 20~24kB.

> 
> The main reason for this change is to simplify SLOB a little bit, make
> it a bit easier to debug whenever something goes wrong.
>

It seems acceptable But I wonder it is worth to increase memory usage
to allow freeing kmem_cache_alloc-ed objects by kfree()?

Thanks,
Hyeonggon

> meminfo right after the system boot, without the patch:
> Slab:              35500 kB
> 
> the same, with the patch:
> Slab:              36396 kB
> 


  parent reply	other threads:[~2021-10-20 11:46 UTC|newest]

Thread overview: 42+ 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
2021-10-12 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 [this message]
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
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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