linux-kernel - Re: [PATCH v5 1/2] lib: stackdepot: Add support to configure STACK_HASH

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Message-ID: <CAG_fn=V8NMcCNof5mekitjAepEZUb4zPHXNNYF+SSiuknuy-BQ@mail.gmail.com>
Date:   Fri, 22 Jan 2021 09:48:43 +0100
From:   Alexander Potapenko <glider@...gle.com>
To:     Vijayanand Jitta <vjitta@...eaurora.org>
Cc:     Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        dan.j.williams@...el.com, broonie@...nel.org,
        Masami Hiramatsu <mhiramat@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>, ylal@...eaurora.org,
        vinmenon@...eaurora.org
Subject: Re: [PATCH v5 1/2] lib: stackdepot: Add support to configure STACK_HASH_SIZE

On Mon, Jan 18, 2021 at 10:57 AM <vjitta@...eaurora.org> wrote:
>
> From: Yogesh Lal <ylal@...eaurora.org>
>
> Use CONFIG_STACK_HASH_ORDER to configure STACK_HASH_SIZE.
>
> Aim is to have configurable value for  STACK_HASH_SIZE,
> so depend on use case one can configure it.
>
> One example is of Page Owner, default value of
> STACK_HASH_SIZE lead stack depot to consume 8MB of static memory.
> Making it configurable and use lower value helps to enable features like
> CONFIG_PAGE_OWNER without any significant overhead.
>
> Signed-off-by: Yogesh Lal <ylal@...eaurora.org>
> Signed-off-by: Vinayak Menon <vinmenon@...eaurora.org>
> Signed-off-by: Vijayanand Jitta <vjitta@...eaurora.org>
Reviewed-by: Alexander Potapenko <glider@...gle.com>

> ---
>  lib/Kconfig      | 9 +++++++++
>  lib/stackdepot.c | 3 +--
>  2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/lib/Kconfig b/lib/Kconfig
> index b46a9fd..96ee125 100644
> --- a/lib/Kconfig
> +++ b/lib/Kconfig
> @@ -651,6 +651,15 @@ config STACKDEPOT
>         bool
>         select STACKTRACE
>
> +config STACK_HASH_ORDER
> +       int "stack depot hash size (12 => 4KB, 20 => 1024KB)"
> +       range 12 20
> +       default 20
> +       depends on STACKDEPOT
> +       help
> +        Select the hash size as a power of 2 for the stackdepot hash table.
> +        Choose a lower value to reduce the memory impact.
> +
>  config SBITMAP
>         bool
>
> diff --git a/lib/stackdepot.c b/lib/stackdepot.c
> index 2caffc6..dff8521 100644
> --- a/lib/stackdepot.c
> +++ b/lib/stackdepot.c
> @@ -142,8 +142,7 @@ static struct stack_record *depot_alloc_stack(unsigned long *entries, int size,
>         return stack;
>  }
>
> -#define STACK_HASH_ORDER 20
> -#define STACK_HASH_SIZE (1L << STACK_HASH_ORDER)
> +#define STACK_HASH_SIZE (1L << CONFIG_STACK_HASH_ORDER)
>  #define STACK_HASH_MASK (STACK_HASH_SIZE - 1)
>  #define STACK_HASH_SEED 0x9747b28c
>
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
> 2.7.4
>


-- 
Alexander Potapenko
Software Engineer

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