From: "Zi Yan" <zi.yan@cs.rutgers.edu>
To: Matthew Wilcox <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org
Subject: Re: [PATCH] mm: Introduce page_size()
Date: Tue, 01 Jan 2019 20:16:26 -0500 [thread overview]
Message-ID: <7342B9ED-D8F3-45F0-B07A-E553478D066C@cs.rutgers.edu> (raw)
In-Reply-To: <20190102005829.GF6310@bombadil.infradead.org>
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On 1 Jan 2019, at 19:58, Matthew Wilcox wrote:
> On Tue, Jan 01, 2019 at 03:11:04PM -0500, Zi Yan wrote:
>> On 1 Jan 2019, at 1:39, Matthew Wilcox wrote:
>>
>>> On Tue, Jan 01, 2019 at 02:02:22AM +0300, Kirill A. Shutemov wrote:
>>>> On Mon, Dec 31, 2018 at 05:42:23AM -0800, Matthew Wilcox wrote:
>>>>> It's unnecessarily hard to find out the size of a potentially huge page.
>>>>> Replace 'PAGE_SIZE << compound_order(page)' with page_size(page).
>>>>
>>>> Good idea.
>>>>
>>>> Should we add page_mask() and page_shift() too?
>>>
>>> I'm not opposed to that at all. I also have a patch to add compound_nr():
>>>
>>> +/* Returns the number of pages in this potentially compound page. */
>>> +static inline unsigned long compound_nr(struct page *page)
>>> +{
>>> + return 1UL << compound_order(page);
>>> +}
>>>
>>> I just haven't sent it yet ;-) It should, perhaps, be called page_count()
>>> or nr_pages() or something. That covers most of the remaining users of
>>> compound_order() which look awkward.
>>
>> We already have hpage_nr_pages() to show the number of pages. Why do we need
>> another one?
>
> Not all compound pages are PMD sized.
Right, and THPs are also compound pages. Maybe using your compound_nr() in
hpage_nr_pages() to factor out the common code if compound_nr() is going to
be added?
--
Best Regards,
Yan Zi
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next prev parent reply other threads:[~2019-01-02 1:16 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-31 13:42 Matthew Wilcox
2018-12-31 23:02 ` Kirill A. Shutemov
2019-01-01 6:39 ` Matthew Wilcox
2019-01-01 20:11 ` Zi Yan
2019-01-02 0:58 ` Matthew Wilcox
2019-01-02 1:16 ` Zi Yan [this message]
2019-01-01 3:27 ` Aneesh Kumar K.V
2019-01-01 3:27 ` Aneesh Kumar K.V
2019-01-01 6:30 ` Matthew Wilcox
2019-01-01 10:11 ` Aneesh Kumar K.V
2019-01-02 3:14 ` Matthew Wilcox
2019-01-02 11:46 ` William Kucharski
2019-01-02 13:09 ` Matthew Wilcox
2019-01-03 10:47 ` William Kucharski
2019-01-01 10:15 ` Aneesh Kumar K.V
2019-05-10 18:12 Matthew Wilcox
2019-05-13 10:56 ` Michal Hocko
2019-05-13 12:43 ` Kirill Tkhai
2019-05-14 11:53 ` William Kucharski
2019-05-22 20:03 ` Andrew Morton
2019-05-23 1:55 ` Matthew Wilcox
2019-05-23 21:33 ` Andrew Morton
2019-05-23 21:44 ` Matthew Wilcox
2019-05-24 6:34 ` Christoph Hellwig
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