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From: Muchun Song <songmuchun@bytedance.com>
To: Oscar Salvador <osalvador@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	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>,
	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>,
	Michal Hocko <mhocko@suse.com>,
	"Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>,
	David Hildenbrand <david@redhat.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>
Subject: Re: [External] Re: [PATCH v8 12/12] mm/hugetlb: Optimize the code with the help of the compiler
Date: Fri, 11 Dec 2020 00:19:50 +0800	[thread overview]
Message-ID: <CAMZfGtUH00bxOptddY0i2Zt2HJsy8C-QgN0aqXGOi=u4-f_MjQ@mail.gmail.com> (raw)
In-Reply-To: <CAMZfGtX842XJC+C_OeptH4Ru_Q-qV1=5vCq_PgPJmuyTGKO_rg@mail.gmail.com>

On Thu, Dec 10, 2020 at 9:29 PM Muchun Song <songmuchun@bytedance.com> wrote:
>
> On Thu, Dec 10, 2020 at 9:16 PM Oscar Salvador <osalvador@suse.de> wrote:
> >
> > On Thu, Dec 10, 2020 at 08:14:18PM +0800, Muchun Song wrote:
> > > Yeah, you are right. But if we do this check can make the code simple.
> > >
> > > For example, here is a code snippet.
> > >
> > > void func(void)
> > > {
> > >         if (free_vmemmap_pages_per_hpage())
> > >                 return;
> > >         /* Do something */
> > > }
> > >
> > > With this patch, the func will be optimized to null when is_power_of_2
> > > returns false.
> > >
> > > void func(void)
> > > {
> > > }
> > >
> > > Without this patch, the compiler cannot do this optimization.
> >
> > Ok, I misread the changelog.
> >
> > So, then is_hugetlb_free_vmemmap_enabled, free_huge_page_vmemmap,
> > free_vmemmap_pages_per_hpage and hugetlb_vmemmap_init are optimized
> > out, right?
>
> Yes, that's right. I have disassembled to make sure of this. Thanks.

Hi Oscar,

Because this is an optimization for code, I leave it in this
separate patch. Do you still suggest squash this with
patch#10? Thanks.

>
> >
> > --
> > Oscar Salvador
> > SUSE L3
>
>
>
> --
> Yours,
> Muchun



-- 
Yours,
Muchun

  reply	other threads:[~2020-12-10 16:21 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-10  3:55 [PATCH v8 00/12] Free some vmemmap pages of HugeTLB page Muchun Song
2020-12-10  3:55 ` [PATCH v8 01/12] mm/memory_hotplug: Factor out bootmem core functions to bootmem_info.c Muchun Song
2020-12-10  3:55 ` [PATCH v8 02/12] mm/hugetlb: Introduce a new config HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2020-12-10  3:55 ` [PATCH v8 03/12] mm/bootmem_info: Introduce free_bootmem_page helper Muchun Song
2020-12-10 14:15   ` Oscar Salvador
2020-12-10 15:22     ` [External] " Muchun Song
2020-12-10 15:26       ` Muchun Song
2020-12-10  3:55 ` [PATCH v8 04/12] mm/hugetlb: Free the vmemmap pages associated with each HugeTLB page Muchun Song
2020-12-10 14:42   ` Oscar Salvador
2020-12-10 14:44     ` Oscar Salvador
2020-12-10 15:58       ` [External] " Muchun Song
2020-12-10 15:57     ` Muchun Song
2020-12-10  3:55 ` [PATCH v8 05/12] mm/hugetlb: Defer freeing of HugeTLB pages Muchun Song
2020-12-10  3:55 ` [PATCH v8 06/12] mm/hugetlb: Allocate the vmemmap pages associated with each HugeTLB page Muchun Song
2020-12-11  9:35   ` Oscar Salvador
2020-12-11 10:52     ` David Hildenbrand
2020-12-11 13:01     ` [External] " Muchun Song
2020-12-10  3:55 ` [PATCH v8 07/12] mm/hugetlb: Set the PageHWPoison to the raw error page Muchun Song
2020-12-10 11:11   ` Muchun Song
2020-12-11 13:36   ` Oscar Salvador
2020-12-11 14:08     ` [External] " Muchun Song
2020-12-10  3:55 ` [PATCH v8 08/12] mm/hugetlb: Flush work when dissolving hugetlb page Muchun Song
2020-12-10  3:55 ` [PATCH v8 09/12] mm/hugetlb: Add a kernel parameter hugetlb_free_vmemmap Muchun Song
2020-12-10 10:04   ` Oscar Salvador
2020-12-10 12:26     ` [External] " Muchun Song
2020-12-10  3:55 ` [PATCH v8 10/12] mm/hugetlb: Introduce nr_free_vmemmap_pages in the struct hstate Muchun Song
2020-12-10 10:15   ` Oscar Salvador
2020-12-10 12:32     ` [External] " Muchun Song
2020-12-10  3:55 ` [PATCH v8 11/12] mm/hugetlb: Gather discrete indexes of tail page Muchun Song
2020-12-10  3:55 ` [PATCH v8 12/12] mm/hugetlb: Optimize the code with the help of the compiler Muchun Song
2020-12-10 10:25   ` Oscar Salvador
2020-12-10 12:14     ` [External] " Muchun Song
2020-12-10 13:16       ` Oscar Salvador
2020-12-10 13:29         ` Muchun Song
2020-12-10 16:19           ` Muchun Song [this message]
2020-12-10  9:18 ` [PATCH v8 00/12] Free some vmemmap pages of HugeTLB page Oscar Salvador

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