From: Christoph Lameter <cl@gentwo.org>
To: Rustam Kovhaev <rkovhaev@gmail.com>
Cc: vbabka@suse.cz, 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 10:22:28 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.22.394.2111221018070.202803@gentwo.de> (raw)
In-Reply-To: <20211122013026.909933-1-rkovhaev@gmail.com>
On Sun, 21 Nov 2021, Rustam Kovhaev wrote:
> Let's prepend both kmalloc() and kmem_cache_alloc() allocations with the
> size header.
> It simplifies the slab API and guarantees that both kmem_cache_alloc()
> and kmalloc() memory could be freed by kfree().
>
> meminfo right after the system boot, x86-64 on xfs, without the patch:
> Slab: 34700 kB
>
> the same, with the patch:
> Slab: 35752 kB
> +#define SLOB_HDR_SIZE max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN)
Ok that is up to 128 bytes on some architectues. Mostly 32 or 64 bytes.
> @@ -307,6 +303,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node,
> unsigned long flags;
> bool _unused;
>
> + size += SLOB_HDR_SIZE;
And every object now has this overhead? 128 bytes extra in extreme cases
per object?
> - if (size < PAGE_SIZE - minalign) {
> - int align = minalign;
> + if (size < PAGE_SIZE - SLOB_HDR_SIZE) {
> + int align = SLOB_HDR_SIZE;
And the object is also aligned to 128 bytes boundaries on some
architectures.
So a 4 byte object occupies 256 bytes in SLOB?
SLOB will no longer be a low memory overhead allocator then.
next prev parent reply other threads:[~2021-11-22 9:28 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 [this message]
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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