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From: Oscar Salvador <osalvador@suse.de>
To: Muchun Song <songmuchun@bytedance.com>
Cc: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de,
	mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com,
	dave.hansen@linux.intel.com, luto@kernel.org,
	peterz@infradead.org, viro@zeniv.linux.org.uk,
	akpm@linux-foundation.org, paulmck@kernel.org,
	mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com,
	rdunlap@infradead.org, oneukum@suse.com,
	anshuman.khandual@arm.com, jroedel@suse.de,
	almasrymina@google.com, rientjes@google.com, willy@infradead.org,
	mhocko@suse.com, song.bao.hua@hisilicon.com, david@redhat.com,
	duanxiongchun@bytedance.com, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v8 09/12] mm/hugetlb: Add a kernel parameter hugetlb_free_vmemmap
Date: Thu, 10 Dec 2020 11:04:54 +0100	[thread overview]
Message-ID: <20201210100454.GB3613@localhost.localdomain> (raw)
In-Reply-To: <20201210035526.38938-10-songmuchun@bytedance.com>

On Thu, Dec 10, 2020 at 11:55:23AM +0800, Muchun Song wrote:
> +hugetlb_free_vmemmap
> +	When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables freeing
> +	unused vmemmap pages associated each HugeTLB page.
                                      ^^^ with

> -	if (end - start < PAGES_PER_SECTION * sizeof(struct page))
> +	if (is_hugetlb_free_vmemmap_enabled())
> +		err = vmemmap_populate_basepages(start, end, node, NULL);
> +	else if (end - start < PAGES_PER_SECTION * sizeof(struct page))
>  		err = vmemmap_populate_basepages(start, end, node, NULL);

Not sure if joining those in an OR makes se.se

>  	else if (boot_cpu_has(X86_FEATURE_PSE))
>  		err = vmemmap_populate_hugepages(start, end, node, altmap);
> @@ -1610,7 +1613,8 @@ void register_page_bootmem_memmap(unsigned long section_nr,
>  		}
>  		get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO);
>  
> -		if (!boot_cpu_has(X86_FEATURE_PSE)) {
> +		if (!boot_cpu_has(X86_FEATURE_PSE) ||
> +		    is_hugetlb_free_vmemmap_enabled()) {

I would add a variable at the beginning called "basepages_populated"
that holds the result of those two conditions.
I am not sure if it slightly improves the code as the conditions do
not need to be rechecked, but the readibility a bit.

> +bool hugetlb_free_vmemmap_enabled;
> +
> +static int __init early_hugetlb_free_vmemmap_param(char *buf)
> +{
> +	if (!buf)
> +		return -EINVAL;
> +
> +	/* We cannot optimize if a "struct page" crosses page boundaries. */

I think this comment belongs to the last patch.


-- 
Oscar Salvador
SUSE L3

  reply	other threads:[~2020-12-10 11:42 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 [this message]
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
2020-12-10  9:18 ` [PATCH v8 00/12] Free some vmemmap pages of HugeTLB page Oscar Salvador

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