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From: Michal Hocko <mhocko@kernel.org>
To: Alexander Duyck <alexander.duyck@gmail.com>
Cc: yang.zhang.wz@gmail.com, pagupta@redhat.com, kvm@vger.kernel.org,
	david@redhat.com, catalin.marinas@arm.com,
	lcapitulino@redhat.com, linux-mm@kvack.org,
	alexander.h.duyck@linux.intel.com, will@kernel.org,
	aarcange@redhat.com, virtio-dev@lists.oasis-open.org,
	mst@redhat.com, willy@infradead.org, wei.w.wang@intel.com,
	ying.huang@intel.com, riel@surriel.com, konrad.wilk@oracle.com,
	dan.j.williams@intel.com, linux-arm-kernel@lists.infradead.org,
	osalvador@suse.de, nitesh@redhat.com, dave.hansen@intel.com,
	linux-kernel@vger.kernel.org, pbonzini@redhat.com,
	akpm@linux-foundation.org, fengguang.wu@intel.com,
	kirill.shutemov@linux.intel.com
Subject: Re: [PATCH v9 2/8] mm: Adjust shuffle code to allow for future coalescing
Date: Tue, 10 Sep 2019 14:20:30 +0200	[thread overview]
Message-ID: <20190910122030.GV2063@dhcp22.suse.cz> (raw)
In-Reply-To: <20190907172520.10910.83100.stgit@localhost.localdomain>

On Sat 07-09-19 10:25:20, Alexander Duyck wrote:
> From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> 
> Move the head/tail adding logic out of the shuffle code and into the
> __free_one_page function since ultimately that is where it is really
> needed anyway. By doing this we should be able to reduce the overhead
> and can consolidate all of the list addition bits in one spot.

This changelog doesn't really explain why we want this. You are
reshuffling the code, allright, but why do we want to reshuffle? Is the
result readability a better code reuse or something else? Where
does the claimed reduced overhead coming from?

From a quick look buddy_merge_likely looks nicer than the code splat
we have. Good.

But then

> Reviewed-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>

[...]

> -	if (is_shuffle_order(order))
> -		add_to_free_area_random(page, &zone->free_area[order],
> -				migratetype);
> +	area = &zone->free_area[order];
> +	if (is_shuffle_order(order) ? shuffle_pick_tail() :
> +	    buddy_merge_likely(pfn, buddy_pfn, page, order))

Ouch this is just awful don't you think?
-- 
Michal Hocko
SUSE Labs

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  parent reply	other threads:[~2019-09-10 12:20 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-07 17:25 [PATCH v9 0/8] stg mail -e --version=v9 \ Alexander Duyck
2019-09-07 17:25 ` [PATCH v9 1/8] mm: Add per-cpu logic to page shuffling Alexander Duyck
2019-09-09  8:14   ` David Hildenbrand
2019-09-09 15:11     ` Alexander Duyck
2019-09-10 12:11       ` Michal Hocko
2019-09-10 22:14         ` Alexander Duyck
2019-09-10 22:11     ` Alexander Duyck
2019-09-09  9:07   ` Kirill A. Shutemov
2019-09-09 15:12     ` Alexander Duyck
2019-09-07 17:25 ` [PATCH v9 2/8] mm: Adjust shuffle code to allow for future coalescing Alexander Duyck
2019-09-09  8:19   ` David Hildenbrand
2019-09-09  9:47   ` Kirill A. Shutemov
2019-09-09 15:22     ` Alexander Duyck
2019-09-09 15:35       ` Kirill A. Shutemov
2019-09-09 15:37         ` Alexander Duyck
2019-09-09 16:43     ` Alexander Duyck
2019-09-09 17:00       ` Kirill A. Shutemov
2019-09-10 12:20   ` Michal Hocko [this message]
2019-09-10 14:48     ` Alexander Duyck
2019-09-07 17:25 ` [PATCH v9 3/8] mm: Move set/get_pcppage_migratetype to mmzone.h Alexander Duyck
2019-09-09  8:22   ` David Hildenbrand
2019-09-09  9:56   ` Kirill A. Shutemov
2019-09-09 18:01     ` Alexander Duyck
2019-09-09 18:12       ` Alexander Duyck
2019-09-10 12:23   ` Michal Hocko
2019-09-10 14:46     ` Alexander Duyck
2019-09-10 17:45       ` Michal Hocko
2019-09-10 20:26         ` Alexander Duyck
2019-09-07 17:25 ` [PATCH v9 4/8] mm: Use zone and order instead of free area in free_list manipulators Alexander Duyck
2019-09-10 12:27   ` Michal Hocko
2019-09-07 17:25 ` [PATCH v9 5/8] arm64: Move hugetlb related definitions out of pgtable.h to page-defs.h Alexander Duyck
2019-09-09  8:52   ` David Hildenbrand
2019-09-09 15:27     ` Alexander Duyck
2019-09-17 17:48   ` Will Deacon
2019-09-17 20:07     ` Alexander Duyck
2019-09-07 17:25 ` [PATCH v9 6/8] mm: Introduce Reported pages Alexander Duyck
2019-09-09 14:42   ` Kirill A. Shutemov
2019-09-09 16:25     ` Alexander Duyck
2019-09-09 16:33       ` Kirill A. Shutemov
2019-09-07 17:26 ` [PATCH v9 7/8] virtio-balloon: Pull page poisoning config out of free page hinting Alexander Duyck
2019-09-09  8:59   ` David Hildenbrand
2019-09-09 15:31     ` Alexander Duyck
2019-09-07 17:26 ` [PATCH v9 8/8] virtio-balloon: Add support for providing unused page reports to host Alexander Duyck
2019-09-07 17:34 ` [PATCH v9 0/8] mm / virtio: Provide support for unused page reporting Alexander Duyck
2019-09-10 12:42 ` [PATCH v9 0/8] stg mail -e --version=v9 \ Michal Hocko
2019-09-10 14:42   ` Alexander Duyck
2019-09-10 14:47     ` Michal Hocko
2019-09-10 16:05       ` Alexander Duyck
2019-09-10 16:18         ` [virtio-dev] " Dr. David Alan Gilbert
2019-09-10 16:22           ` David Hildenbrand
2019-09-11  9:23             ` Michael S. Tsirkin
2019-09-11  9:50               ` David Hildenbrand
2019-09-10 17:52         ` Michal Hocko
2019-09-10 18:00           ` Michal Hocko
2019-09-10 20:37             ` Alexander Duyck
2019-09-10 21:23           ` Alexander Duyck
2019-09-11 11:36             ` Michal Hocko
2019-09-11 11:47               ` David Hildenbrand
2019-09-11 12:08               ` Michael S. Tsirkin
2019-09-11 12:19                 ` Michal Hocko
2019-09-11 12:25                   ` Michal Hocko
2019-09-11 12:42                     ` David Hildenbrand
2019-09-11 12:54                       ` Michal Hocko
2019-09-11 13:03                         ` David Hildenbrand
2019-09-11 13:20                           ` Michal Hocko
2019-09-11 13:51                             ` Michal Hocko
2019-09-11 16:09                               ` David Hildenbrand
2019-09-12  7:16                                 ` Michal Hocko
2019-09-12  7:47                                   ` David Hildenbrand
2019-09-12  9:26                                     ` Michal Hocko
2019-09-12 12:00                                     ` Nitesh Narayan Lal
2019-09-11 14:03                             ` Nitesh Narayan Lal
2019-09-11 16:02                             ` David Hildenbrand
2019-09-11 13:19                         ` Nitesh Narayan Lal
2019-09-11 12:55                       ` Nitesh Narayan Lal
2019-09-11 15:12               ` Alexander Duyck
2019-09-12  9:19                 ` Michal Hocko
2019-09-12 10:24                   ` Kirill A. Shutemov
2019-09-12 11:11                     ` Michal Hocko
2019-09-12 15:42                   ` Alexander Duyck
2019-09-12 16:35                   ` Mel Gorman
2019-09-12 17:48                     ` Alexander Duyck

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