From: David Hildenbrand <david@redhat.com>
To: Miaohe Lin <linmiaohe@huawei.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] mm/swapfile: avoid confusing swap cache statistics
Date: Tue, 31 May 2022 14:58:21 +0200 [thread overview]
Message-ID: <33d6aec8-b4fc-aa37-27f4-f33984ea33d3@redhat.com> (raw)
In-Reply-To: <c7d6fec7-039d-2f54-c3b3-95deb7417a73@huawei.com>
On 31.05.22 04:55, Miaohe Lin wrote:
> On 2022/5/31 7:04, Andrew Morton wrote:
>> On Fri, 27 May 2022 17:26:25 +0800 Miaohe Lin <linmiaohe@huawei.com> wrote:
>>
>>> At swapoff time, we're going to swap in the pages continuously. So calling
>>> lookup_swap_cache would confuse statistics. We should use find_get_page
>>> directly here.
>>
>> Why is the existing behaviour wrong? swapoff() has to swap stuff in to
>> be able to release the swap device. Why do you believe that this
>> swapin activity should not be accounted?
>
> IMHO, statistics, e.g. swap_cache_info.find_success, are used to show the effectiveness
> of the swap cache activity. So they should only reflect the memory accessing activity
> of the user. I think swapoff can't reflect the effectiveness of the swap cache activity
> because it just swaps in pages one by one. Or statistics should reflect all the activity
> of the user including swapoff?
I'm wondering who cares and why?
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2022-05-31 12:58 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-27 9:26 [PATCH 0/3] A few fixup patches for swap Miaohe Lin
2022-05-27 9:26 ` [PATCH 1/3] mm/swapfile: make security_vm_enough_memory_mm() work as expected Miaohe Lin
2022-05-30 23:02 ` Andrew Morton
2022-05-31 2:40 ` Miaohe Lin
2022-05-27 9:26 ` [PATCH 2/3] mm/swapfile: avoid confusing swap cache statistics Miaohe Lin
2022-05-30 23:04 ` Andrew Morton
2022-05-31 2:55 ` Miaohe Lin
2022-05-31 12:58 ` David Hildenbrand [this message]
2022-06-01 2:11 ` Miaohe Lin
2022-06-01 7:53 ` David Hildenbrand
2022-06-02 7:29 ` Miaohe Lin
2022-06-02 8:41 ` David Hildenbrand
2022-06-06 3:14 ` Miaohe Lin
2022-05-27 9:26 ` [PATCH 3/3] mm/swapfile: fix possible data races of inuse_pages Miaohe Lin
2022-05-31 13:02 ` David Hildenbrand
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