From: Minchan Kim <minchan@kernel.org>
To: Jerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Mahendran Ganesh <opensource.ganesh@gmail.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/zsmalloc: simplify zs_max_alloc_size handling
Date: Fri, 30 Jun 2017 10:24:36 +0900 [thread overview]
Message-ID: <20170630012436.GA24520@bbox> (raw)
In-Reply-To: <20170628081420.26898-1-jmarchan@redhat.com>
Hi Jerome,
On Wed, Jun 28, 2017 at 10:14:20AM +0200, Jerome Marchand wrote:
> Commit 40f9fb8cffc6 ("mm/zsmalloc: support allocating obj with size of
> ZS_MAX_ALLOC_SIZE") fixes a size calculation error that prevented
> zsmalloc to allocate an object of the maximal size
> (ZS_MAX_ALLOC_SIZE). I think however the fix is unneededly
> complicated.
>
> This patch replaces the dynamic calculation of zs_size_classes at init
> time by a compile time calculation that uses the DIV_ROUND_UP() macro
> already used in get_size_class_index().
>
> Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
> ---
> mm/zsmalloc.c | 52 +++++++++++++++-------------------------------------
> 1 file changed, 15 insertions(+), 37 deletions(-)
>
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index d41edd2..134024b 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -116,6 +116,11 @@
> #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
> #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
>
> +#define FULLNESS_BITS 2
> +#define CLASS_BITS 8
> +#define ISOLATED_BITS 3
> +#define MAGIC_VAL_BITS 8
> +
> #define MAX(a, b) ((a) >= (b) ? (a) : (b))
> /* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
> #define ZS_MIN_ALLOC_SIZE \
> @@ -137,6 +142,8 @@
> * (reason above)
> */
> #define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> CLASS_BITS)
> +#define ZS_SIZE_CLASSES DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \
> + ZS_SIZE_CLASS_DELTA)
#define ZS_SIZE_CLASSES (DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \
ZS_SIZE_CLASS_DELTA) + 1)
I think it should add +1 to cover ZS_MIN_ALLOC_SIZE.
Otherwise, looks good to me.
Thanks.
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next prev parent reply other threads:[~2017-06-30 1:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-28 8:14 [PATCH] mm/zsmalloc: simplify zs_max_alloc_size handling Jerome Marchand
2017-06-30 1:24 ` Minchan Kim [this message]
2017-06-30 11:43 ` Jerome Marchand
2017-06-30 11:48 ` [PATCH v2] " Jerome Marchand
2017-07-03 2:13 ` Minchan Kim
2017-07-03 2:16 ` Minchan Kim
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