From: "Huang\, Ying" <ying.huang@intel.com>
To: Vasily Averin <vvs@virtuozzo.com>
Cc: <linux-mm@kvack.org>, Andrew Morton <akpm@linux-foundation.org>,
<linux-kernel@vger.kernel.org>, "Aaron Lu" <aaron.lu@intel.com>
Subject: Re: [PATCH 2/2] mm: avoid unnecessary swap_info_struct allocation
Date: Mon, 05 Nov 2018 08:57:05 +0800 [thread overview]
Message-ID: <87sh0gbau6.fsf@yhuang-dev.intel.com> (raw)
In-Reply-To: <a24bf353-8715-2bee-d0fa-96ca06c5b69f@virtuozzo.com> (Vasily Averin's message of "Mon, 5 Nov 2018 01:13:12 +0300")
Vasily Averin <vvs@virtuozzo.com> writes:
> Currently newly allocated swap_info_struct can be quickly freed.
> This patch avoid uneccessary high-order page allocation and helps
> to decrease the memory pressure.
I think swapon/swapoff are rare operations, so it will not increase the
memory pressure much.
Best Regards,
Huang, Ying
> Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
> ---
> mm/swapfile.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 8688ae65ef58..53ec2f0cdf26 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -2809,14 +2809,17 @@ late_initcall(max_swapfiles_check);
>
> static struct swap_info_struct *alloc_swap_info(void)
> {
> - struct swap_info_struct *p;
> + struct swap_info_struct *p = NULL;
> unsigned int type;
> int i;
> + bool force_alloc = false;
>
> - p = kvzalloc(sizeof(*p), GFP_KERNEL);
> - if (!p)
> - return ERR_PTR(-ENOMEM);
> -
> +retry:
> + if (force_alloc) {
> + p = kvzalloc(sizeof(*p), GFP_KERNEL);
> + if (!p)
> + return ERR_PTR(-ENOMEM);
> + }
> spin_lock(&swap_lock);
> for (type = 0; type < nr_swapfiles; type++) {
> if (!(swap_info[type]->flags & SWP_USED))
> @@ -2828,6 +2831,11 @@ static struct swap_info_struct *alloc_swap_info(void)
> return ERR_PTR(-EPERM);
> }
> if (type >= nr_swapfiles) {
> + if (!force_alloc) {
> + force_alloc = true;
> + spin_unlock(&swap_lock);
> + goto retry;
> + }
> p->type = type;
> swap_info[type] = p;
> /*
next prev parent reply other threads:[~2018-11-05 0:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-04 22:13 [PATCH 2/2] mm: avoid unnecessary swap_info_struct allocation Vasily Averin
2018-11-05 0:57 ` Huang, Ying [this message]
2018-11-05 5:19 ` Vasily Averin
2018-11-05 10:41 ` Vasily Averin
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