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From: Oscar Salvador <osalvador@suse.de>
To: Michal Hocko <mhocko@suse.com>
Cc: "Muchun Song" <songmuchun@bytedance.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Mike Kravetz" <mike.kravetz@oracle.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>,
	bp@alien8.de, x86@kernel.org, hpa@zytor.com,
	dave.hansen@linux.intel.com, luto@kernel.org,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	paulmck@kernel.org, mchehab+huawei@kernel.org,
	pawan.kumar.gupta@linux.intel.com,
	"Randy Dunlap" <rdunlap@infradead.org>,
	oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de,
	"Mina Almasry" <almasrymina@google.com>,
	"David Rientjes" <rientjes@google.com>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>,
	"David Hildenbrand" <david@redhat.com>,
	"HORIGUCHI NAOYA(堀口 直也)" <naoya.horiguchi@nec.com>,
	"Joao Martins" <joao.m.martins@oracle.com>,
	"Xiongchun duan" <duanxiongchun@bytedance.com>,
	linux-doc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	"Linux Memory Management List" <linux-mm@kvack.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	"Miaohe Lin" <linmiaohe@huawei.com>,
	"Chen Huang" <chenhuang5@huawei.com>,
	"Bodeddula Balasubramaniam" <bodeddub@amazon.com>
Subject: Re: [External] Re: [PATCH v18 9/9] mm: hugetlb: optimize the code with the help of the compiler
Date: Thu, 11 Mar 2021 14:45:35 +0100	[thread overview]
Message-ID: <20210311134531.GA24797@linux> (raw)
In-Reply-To: <YEoKJYzP8//qVebC@dhcp22.suse.cz>

On Thu, Mar 11, 2021 at 01:16:37PM +0100, Michal Hocko wrote:
> On Thu 11-03-21 18:00:09, Muchun Song wrote:
> [...]
> > Sorry. I am confused why you disagree with this change.
> > It does not bring any disadvantages.
> 
> Because it is adding a code which is not really necessary and which will
> have to be maintained. Think of future changes which would need to grow
> more of these. Hugetlb code paths shouldn't really think about size of
> the struct page.

I have to confess that when I looked at the patch I found it nice in the way that
wipes out almost all clode dealing with vmemmap when sizeof(struct page) != power_of_2,
and I was convinced by the fact that only two places required the change.
So all in all it did not look like much churn, and not __that__ hard to maintain.

But I did not think in the case where this trick needs to be spread in more places
if the code changes over time.

So I agree that although it gets rid of a lot of code, it would seldomly pay off as
not many configuration out there are running on !power_of_2, and hugetlb is already
tricky enough.


-- 
Oscar Salvador
SUSE L3

      parent reply	other threads:[~2021-03-11 13:46 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-08 10:27 [PATCH v18 0/9] Free some vmemmap pages of HugeTLB page Muchun Song
2021-03-08 10:27 ` [PATCH v18 1/9] mm: memory_hotplug: factor out bootmem core functions to bootmem_info.c Muchun Song
2021-03-10 14:14   ` Michal Hocko
2021-03-11  2:58     ` [External] " Muchun Song
2021-03-11  8:45       ` Muchun Song
2021-03-11  8:53         ` Michal Hocko
2021-03-11  9:05           ` Muchun Song
2021-03-08 10:28 ` [PATCH v18 2/9] mm: hugetlb: introduce a new config HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2021-03-08 10:28 ` [PATCH v18 3/9] mm: hugetlb: free the vmemmap pages associated with each HugeTLB page Muchun Song
2021-03-10 14:32   ` Michal Hocko
2021-03-11  3:35     ` [External] " Muchun Song
2021-03-08 10:28 ` [PATCH v18 4/9] mm: hugetlb: alloc " Muchun Song
2021-03-10 14:21   ` Oscar Salvador
2021-03-11  4:13     ` [External] " Muchun Song
2021-03-10 15:19   ` Michal Hocko
2021-03-10 18:56     ` Mike Kravetz
2021-03-10 21:11       ` Michal Hocko
2021-03-10 21:49         ` Paul E. McKenney
2021-03-10 22:10           ` Mike Kravetz
2021-03-10 23:28             ` Paul E. McKenney
2021-03-11  8:40               ` Michal Hocko
2021-03-11 12:17                 ` Michal Hocko
2021-03-11 17:59                   ` Mike Kravetz
2021-03-11 22:53                     ` Mike Kravetz
2021-03-12  8:15                       ` Michal Hocko
2021-03-12 17:50                         ` Mike Kravetz
2021-03-11  4:26     ` [External] " Muchun Song
2021-03-11  8:46       ` Michal Hocko
2021-03-11  8:49         ` Muchun Song
2021-03-08 10:28 ` [PATCH v18 5/9] mm: hugetlb: set the PageHWPoison to the raw error page Muchun Song
2021-03-10 15:27   ` Michal Hocko
2021-03-11  6:34     ` [External] " Muchun Song
2021-03-11  8:50       ` Michal Hocko
2021-03-11  9:13         ` Muchun Song
2021-03-08 10:28 ` [PATCH v18 6/9] mm: hugetlb: add a kernel parameter hugetlb_free_vmemmap Muchun Song
2021-03-10 15:37   ` Michal Hocko
2021-03-10 17:15     ` Randy Dunlap
2021-03-11  6:36       ` [External] " Muchun Song
2021-03-11  6:36     ` Muchun Song
2021-03-08 10:28 ` [PATCH v18 7/9] mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate Muchun Song
2021-03-08 10:28 ` [PATCH v18 8/9] mm: hugetlb: gather discrete indexes of tail page Muchun Song
2021-03-10 15:39   ` Michal Hocko
2021-03-08 10:28 ` [PATCH v18 9/9] mm: hugetlb: optimize the code with the help of the compiler Muchun Song
2021-03-10 15:41   ` Michal Hocko
2021-03-11  7:33     ` [External] " Muchun Song
2021-03-11  8:55       ` Michal Hocko
2021-03-11  9:08         ` Muchun Song
2021-03-11  9:39           ` Michal Hocko
2021-03-11 10:00             ` Muchun Song
2021-03-11 12:16               ` Michal Hocko
2021-03-11 13:00                 ` Muchun Song
2021-03-11 13:45                 ` Oscar Salvador [this message]

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