From: Tim Chen <tim.c.chen@linux.intel.com>
To: Zhen Lei <thunder.leizhen@huawei.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] mm/swap: remove redundant check for swap_slot_cache_initialized
Date: Fri, 1 May 2020 15:35:27 -0700 [thread overview]
Message-ID: <9b45c120-e369-d436-a369-6c80e3d6ee2e@linux.intel.com> (raw)
In-Reply-To: <20200430061143.450-4-thunder.leizhen@huawei.com>
On 4/29/20 11:11 PM, Zhen Lei wrote:
> Because enable_swap_slots_cache can only become true in
> enable_swap_slots_cache(), and depends on swap_slot_cache_initialized is
> true before. That means, when enable_swap_slots_cache is true,
> swap_slot_cache_initialized is true also.
>
> So the condition:
> "swap_slot_cache_enabled && swap_slot_cache_initialized"
> can be reduced to "swap_slot_cache_enabled"
>
> And in mathematics:
> "!swap_slot_cache_enabled || !swap_slot_cache_initialized"
> is equal to "!(swap_slot_cache_enabled && swap_slot_cache_initialized)"
>
> So no functional change.
>
> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> ---
> mm/swap_slots.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/mm/swap_slots.c b/mm/swap_slots.c
> index b40394473a3c..3e6453573a89 100644
> --- a/mm/swap_slots.c
> +++ b/mm/swap_slots.c
> @@ -46,8 +46,7 @@ static void __drain_swap_slots_cache(unsigned int type);
> static void deactivate_swap_slots_cache(void);
> static void reactivate_swap_slots_cache(void);
>
> -#define use_swap_slot_cache (swap_slot_cache_active && \
> - swap_slot_cache_enabled && swap_slot_cache_initialized)
> +#define use_swap_slot_cache (swap_slot_cache_active && swap_slot_cache_enabled)
Yes, swap_slot_cache_enabled does imply swap_slot_cache_initialized
in current code. So checking swap_slot_cache_enabled is
enough here.
> #define SLOTS_CACHE 0x1
> #define SLOTS_CACHE_RET 0x2
>
> @@ -94,7 +93,7 @@ static bool check_cache_active(void)
> {
> long pages;
>
> - if (!swap_slot_cache_enabled || !swap_slot_cache_initialized)
> + if (!swap_slot_cache_enabled)
This simplification is okay. !swap_slot_cache_initialize implies !swap_slot_cache_enabled.
So only !swap_slot_cache_enabled needs to be checked.
> return false;
>
> pages = get_nr_swap_pages();
>
Acked-by: Tim Chen <tim.c.chen@linux.intel.com>
next prev parent reply other threads:[~2020-05-01 22:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-30 6:11 [PATCH 0/3] clean up some functions in mm/swap_slots.c Zhen Lei
2020-04-30 6:11 ` [PATCH 1/3] mm/swap: simplify alloc_swap_slot_cache() Zhen Lei
2020-05-01 21:46 ` Tim Chen
2020-04-30 6:11 ` [PATCH 2/3] mm/swap: simplify enable_swap_slots_cache() Zhen Lei
2020-05-01 21:59 ` Tim Chen
2020-04-30 6:11 ` [PATCH 3/3] mm/swap: remove redundant check for swap_slot_cache_initialized Zhen Lei
2020-05-01 22:35 ` Tim Chen [this message]
2020-07-08 9:27 ` [PATCH 0/3] clean up some functions in mm/swap_slots.c Leizhen (ThunderTown)
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