From: Wei Yang <richard.weiyang@gmail.com>
To: Jia He <hejianet@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Mel Gorman <mgorman@suse.de>, Will Deacon <will.deacon@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Pavel Tatashin <pasha.tatashin@oracle.com>,
Daniel Jordan <daniel.m.jordan@oracle.com>,
AKASHI Takahiro <takahiro.akashi@linaro.org>,
Gioh Kim <gi-oh.kim@profitbricks.com>,
Steven Sistare <steven.sistare@oracle.com>,
Daniel Vacek <neelx@redhat.com>,
Eugeniu Rosca <erosca@de.adit-jv.com>,
Vlastimil Babka <vbabka@suse.cz>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
James Morse <james.morse@arm.com>,
Steve Capper <steve.capper@arm.com>,
x86@kernel.org, Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Kate Stewart <kstewart@linuxfoundation.org>,
Philippe Ombredanne <pombredanne@nexb.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Kemi Wang <kemi.wang@intel.com>, Petr Tesarik <ptesarik@suse.com>,
YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Nikolay Borisov <nborisov@suse.com>
Subject: Re: [PATCH v3 0/5] optimize memblock_next_valid_pfn and early_pfn_valid
Date: Wed, 28 Mar 2018 10:36:38 +0800 [thread overview]
Message-ID: <20180328023638.GA94065@WeideMacBook-Pro.local> (raw)
In-Reply-To: <49fefc1c-81dd-98f8-7da5-5b5e85d919e4@gmail.com>
On Wed, Mar 28, 2018 at 09:45:33AM +0800, Jia He wrote:
>
>
>On 3/28/2018 8:30 AM, Wei Yang Wrote:
>> On Tue, Mar 27, 2018 at 03:15:08PM +0800, Jia He wrote:
>> >
>> > On 3/27/2018 9:02 AM, Wei Yang Wrote:
>> > > On Sun, Mar 25, 2018 at 08:02:14PM -0700, Jia He wrote:
>> > > > Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns
>> > > > where possible") tried to optimize the loop in memmap_init_zone(). But
>> > > > there is still some room for improvement.
>> > > >
>> > > > Patch 1 remain the memblock_next_valid_pfn when CONFIG_HAVE_ARCH_PFN_VALID
>> > > > is enabled
>> > > > Patch 2 optimizes the memblock_next_valid_pfn()
>> > > > Patch 3~5 optimizes the early_pfn_valid(), I have to split it into parts
>> > > > because the changes are located across subsystems.
>> > > >
>> > > > I tested the pfn loop process in memmap_init(), the same as before.
>> > > > As for the performance improvement, after this set, I can see the time
>> > > > overhead of memmap_init() is reduced from 41313 us to 24345 us in my
>> > > > armv8a server(QDF2400 with 96G memory).
>> > > >
>> > > > Attached the memblock region information in my server.
>> > > > [ 86.956758] Zone ranges:
>> > > > [ 86.959452] DMA [mem 0x0000000000200000-0x00000000ffffffff]
>> > > > [ 86.966041] Normal [mem 0x0000000100000000-0x00000017ffffffff]
>> > > > [ 86.972631] Movable zone start for each node
>> > > > [ 86.977179] Early memory node ranges
>> > > > [ 86.980985] node 0: [mem 0x0000000000200000-0x000000000021ffff]
>> > > > [ 86.987666] node 0: [mem 0x0000000000820000-0x000000000307ffff]
>> > > > [ 86.994348] node 0: [mem 0x0000000003080000-0x000000000308ffff]
>> > > > [ 87.001029] node 0: [mem 0x0000000003090000-0x00000000031fffff]
>> > > > [ 87.007710] node 0: [mem 0x0000000003200000-0x00000000033fffff]
>> > > > [ 87.014392] node 0: [mem 0x0000000003410000-0x000000000563ffff]
>> > > > [ 87.021073] node 0: [mem 0x0000000005640000-0x000000000567ffff]
>> > > > [ 87.027754] node 0: [mem 0x0000000005680000-0x00000000056dffff]
>> > > > [ 87.034435] node 0: [mem 0x00000000056e0000-0x00000000086fffff]
>> > > > [ 87.041117] node 0: [mem 0x0000000008700000-0x000000000871ffff]
>> > > > [ 87.047798] node 0: [mem 0x0000000008720000-0x000000000894ffff]
>> > > > [ 87.054479] node 0: [mem 0x0000000008950000-0x0000000008baffff]
>> > > > [ 87.061161] node 0: [mem 0x0000000008bb0000-0x0000000008bcffff]
>> > > > [ 87.067842] node 0: [mem 0x0000000008bd0000-0x0000000008c4ffff]
>> > > > [ 87.074524] node 0: [mem 0x0000000008c50000-0x0000000008e2ffff]
>> > > > [ 87.081205] node 0: [mem 0x0000000008e30000-0x0000000008e4ffff]
>> > > > [ 87.087886] node 0: [mem 0x0000000008e50000-0x0000000008fcffff]
>> > > > [ 87.094568] node 0: [mem 0x0000000008fd0000-0x000000000910ffff]
>> > > > [ 87.101249] node 0: [mem 0x0000000009110000-0x00000000092effff]
>> > > > [ 87.107930] node 0: [mem 0x00000000092f0000-0x000000000930ffff]
>> > > > [ 87.114612] node 0: [mem 0x0000000009310000-0x000000000963ffff]
>> > > > [ 87.121293] node 0: [mem 0x0000000009640000-0x000000000e61ffff]
>> > > > [ 87.127975] node 0: [mem 0x000000000e620000-0x000000000e64ffff]
>> > > > [ 87.134657] node 0: [mem 0x000000000e650000-0x000000000fffffff]
>> > > > [ 87.141338] node 0: [mem 0x0000000010800000-0x0000000017feffff]
>> > > > [ 87.148019] node 0: [mem 0x000000001c000000-0x000000001c00ffff]
>> > > > [ 87.154701] node 0: [mem 0x000000001c010000-0x000000001c7fffff]
>> > > > [ 87.161383] node 0: [mem 0x000000001c810000-0x000000007efbffff]
>> > > > [ 87.168064] node 0: [mem 0x000000007efc0000-0x000000007efdffff]
>> > > > [ 87.174746] node 0: [mem 0x000000007efe0000-0x000000007efeffff]
>> > > > [ 87.181427] node 0: [mem 0x000000007eff0000-0x000000007effffff]
>> > > > [ 87.188108] node 0: [mem 0x000000007f000000-0x00000017ffffffff]
>> > > Hi, Jia
>> > >
>> > > I haven't taken a deep look into your code, just one curious question on your
>> > > memory layout.
>> > >
>> > > The log above is printed out in free_area_init_nodes(), which iterates on
>> > > memblock.memory and prints them. If I am not wrong, memory regions added to
>> > > memblock.memory are ordered and merged if possible.
>> > >
>> > > While from your log, I see many regions could be merged but are isolated. For
>> > > example, the last two region:
>> > >
>> > > node 0: [mem 0x000000007eff0000-0x000000007effffff]
>> > > node 0: [mem 0x000000007f000000-0x00000017ffffffff]
>> > >
>> > > So I am curious why they are isolated instead of combined to one.
>> > >
>> > > >From the code, the possible reason is the region's flag differs from each
>> > > other. If you have time, would you mind taking a look into this?
>> > >
>> > Hi Wei
>> > I thought these 2 have different flags
>> > [ 0.000000] idx=30,region [7eff0000:10000]flag=4 <--- aka
>> > MEMBLOCK_NOMAP
>> > [ 0.000000] node 0: [mem 0x000000007eff0000-0x000000007effffff]
>> > [ 0.000000] idx=31,region [7f000000:81000000]flag=0 <--- aka MEMBLOCK_NONE
>> > [ 0.000000] node 0: [mem 0x000000007f000000-0x00000017ffffffff]
>> Thanks.
>>
>> Hmm, I am not that familiar with those flags, while they look like to indicate
>> the physical capability of this range.
>>
>> MEMBLOCK_NONE no special
>> MEMBLOCK_HOTPLUG hotplug-able
>> MEMBLOCK_MIRROR high reliable
>> MEMBLOCK_NOMAP no direct map
>>
>> While these flags are not there when they are first added into the memory
>> region. When you look at the memblock_add_range(), the last parameter passed
>> is always 0. This means current several separated ranges reflect the physical
>> memory capability layout.
>>
>> Then, why this layout is so scattered? As you can see several ranges are less
>> than 1M.
>>
>> If, just my assumption, we could merge some of them, we could have a better
>> performance. Less ranges, less searching time.
>Thanks for your suggestions, Wei
>Need further digging and will consider to improve it in another patchset.
>
You are welcome :-)
I am glad to see your further patchset or investigation, if you are willing me
to involve.
>--
>Cheers,
>Jia
--
Wei Yang
Help you, Help me
prev parent reply other threads:[~2018-03-28 2:36 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-26 3:02 Jia He
2018-03-26 3:02 ` [PATCH v3 1/5] mm: page_alloc: remain memblock_next_valid_pfn() when CONFIG_HAVE_ARCH_PFN_VALID is enable Jia He
2018-03-28 9:18 ` Wei Yang
2018-03-28 9:49 ` Jia He
2018-04-02 8:12 ` Wei Yang
2018-04-02 9:17 ` Jia He
2018-04-03 0:14 ` Wei Yang
2018-03-26 3:02 ` [PATCH v3 2/5] mm: page_alloc: reduce unnecessary binary search in memblock_next_valid_pfn() Jia He
2018-03-27 17:17 ` Daniel Vacek
2018-03-28 2:09 ` Jia He
2018-03-28 9:26 ` Wei Yang
2018-03-29 8:06 ` Jia He
2018-03-30 1:43 ` Wei Yang
2018-03-30 2:12 ` Jia He
2018-03-26 3:02 ` [PATCH v3 3/5] mm/memblock: introduce memblock_search_pfn_regions() Jia He
2018-03-26 3:02 ` [PATCH v3 4/5] arm64: introduce pfn_valid_region() Jia He
2018-03-28 9:38 ` Wei Yang
2018-03-26 3:02 ` [PATCH v3 5/5] mm: page_alloc: reduce unnecessary binary search in early_pfn_valid() Jia He
2018-03-27 17:51 ` Daniel Vacek
2018-03-28 2:10 ` Jia He
2018-03-27 1:02 ` [PATCH v3 0/5] optimize memblock_next_valid_pfn and early_pfn_valid Wei Yang
2018-03-27 7:15 ` Jia He
2018-03-28 0:30 ` Wei Yang
2018-03-28 1:45 ` Jia He
2018-03-28 2:36 ` Wei Yang [this message]
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