From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1754025AbcI2HKC (ORCPT <rfc822;w@1wt.eu>);
        Thu, 29 Sep 2016 03:10:02 -0400
Received: from out0-151.mail.aliyun.com ([140.205.0.151]:53499 "EHLO
        out0-151.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S932170AbcI2HJx (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 29 Sep 2016 03:09:53 -0400
X-Greylist: delayed 317 seconds by postgrey-1.27 at vger.kernel.org; Thu, 29 Sep 2016 03:09:53 EDT
X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R341e4;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e02c03305;MF=hillf.zj@alibaba-inc.com;NM=1;PH=DS;RN=17;SR=0;TI=SMTPD_---.70-qmFg_1475132644;
Reply-To: "Hillf Danton" <hillf.zj@alibaba-inc.com>
From: "Hillf Danton" <hillf.zj@alibaba-inc.com>
To: <tim.c.chen@linux.intel.com>,
        "'Andrew Morton'" <akpm@linux-foundation.org>
Cc: <dave.hansen@intel.com>, <andi.kleen@intel.com>, <aaron.lu@intel.com>,
        <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        "'Huang Ying'" <ying.huang@intel.com>,
        "'Hugh Dickins'" <hughd@google.com>, "'Shaohua Li'" <shli@kernel.org>,
        "'Minchan Kim'" <minchan@kernel.org>,
        "'Rik van Riel'" <riel@redhat.com>,
        "'Andrea Arcangeli'" <aarcange@redhat.com>,
        "'Kirill A . Shutemov'" <kirill.shutemov@linux.intel.com>,
        "'Vladimir Davydov'" <vdavydov@virtuozzo.com>,
        "'Johannes Weiner'" <hannes@cmpxchg.org>,
        "'Michal Hocko'" <mhocko@kernel.org>
References: <20160927171858.GA17943@linux.intel.com>
In-Reply-To: <20160927171858.GA17943@linux.intel.com>
Subject: Re: [PATCH 7/8] mm/swap: Add cache for swap slots allocation
Date: Thu, 29 Sep 2016 15:04:03 +0800
Message-ID: <008401d21a1f$aa29a510$fe7cef30$@alibaba-inc.com>
MIME-Version: 1.0
Content-Type: text/plain;
        charset="us-ascii"
Content-Transfer-Encoding: 7bit
X-Mailer: Microsoft Outlook 14.0
Thread-Index: AQGFS04DUSwt+PV4TdsmDTCPbR0TV6EppY0g
Content-Language: zh-cn
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wednesday, September 28, 2016 1:19 AM Tim Chen wrote
[...]
> +
> +static int alloc_swap_slot_cache(int cpu)
> +{
> +	struct swap_slots_cache *cache;
> +
> +	cache = &per_cpu(swp_slots, cpu);
> +	mutex_init(&cache->alloc_lock);
> +	spin_lock_init(&cache->free_lock);
> +	cache->nr = 0;
> +	cache->cur = 0;
> +	cache->n_ret = 0;
> +	cache->slots = vzalloc(sizeof(swp_entry_t) * SWAP_SLOTS_CACHE_SIZE);
> +	if (!cache->slots) {
> +		swap_slot_cache_enabled = false;
> +		return -ENOMEM;
> +	}
> +	cache->slots_ret = vzalloc(sizeof(swp_entry_t) * SWAP_SLOTS_CACHE_SIZE);
> +	if (!cache->slots_ret) {
> +		vfree(cache->slots);
> +		swap_slot_cache_enabled = false;
> +		return -ENOMEM;
> +	}
> +	return 0;
> +}
> +
[...]
> +
> +static void free_slot_cache(int cpu)
> +{
> +	struct swap_slots_cache *cache;
> +
> +	mutex_lock(&swap_slots_cache_mutex);
> +	drain_slots_cache_cpu(cpu, SLOTS_CACHE | SLOTS_CACHE_RET);
> +	cache = &per_cpu(swp_slots, cpu);
> +	cache->nr = 0;
> +	cache->cur = 0;
> +	cache->n_ret = 0;
> +	vfree(cache->slots);

Also free cache->slots_ret?
Or fold the relevant two allocations into one?
 
> +	mutex_unlock(&swap_slots_cache_mutex);
> +}
> 
thanks
Hillf