Re: makedumpfile mmap() benchmark

From: Jingbai Ma
Date: Wed Mar 27 2013 - 02:35:41 EST


On 03/27/2013 02:23 PM, HATAYAMA Daisuke wrote:
From: Jingbai Ma<jingbai.ma@xxxxxx>
Subject: makedumpfile mmap() benchmark
Date: Wed, 27 Mar 2013 13:51:37 +0800

Hi,

I have tested the makedumpfile mmap patch on a machine with 2TB
memory, here is testing results:

Thanks for your benchmark. It's very helpful to see the benchmark on
different environments.

Thanks for your patch, there is a great performance improvement, very impressive!


Test environment:
Machine: HP ProLiant DL980 G7 with 2TB RAM.
CPU: Intel(R) Xeon(R) CPU E7- 2860 @ 2.27GHz (8 sockets, 10 cores)
(Only 1 cpu was enabled the 2nd kernel)
Kernel: 3.9.0-rc3+ with mmap kernel patch v3
vmcore size: 2.0TB
Dump file size: 3.6GB
makedumpfile mmap branch with parameters: -c --message-level 23 -d 31
--map-size<map-size>

To reduce the benchmark time, I recommend LZO or snappy compressions
rather than zlib. zlib is used when -c option is specified, and it's
too slow for use of crash dump.

That's a very helpful suggestion, I will try it again with LZO/snappy lib again.


To build makedumpfile with each compression format supports, do
USELZO=on or USESNAPPY=on after installing necessary libraries.

All measured time from debug message of makedumpfile.

As a comparison, I also have tested with original kernel and original
makedumpfile 1.5.1 and 1.5.3.
I added all [Excluding unnecessary pages] and [Excluding free pages]
time together as "Filter Pages", and [Copyying Data] as "Copy data"
here.

makedumjpfile Kernel map-size (KB) Filter pages (s) Copy data (s)
Total (s)
1.5.1 3.7.0-0.36.el7.x86_64 N/A 940.28 1269.25 2209.53
1.5.3 3.7.0-0.36.el7.x86_64 N/A 380.09 992.77 1372.86
1.5.3 v3.9-rc3 N/A 197.77 892.27 1090.04
1.5.3+mmap v3.9-rc3+mmap 0 164.87 606.06 770.93
1.5.3+mmap v3.9-rc3+mmap 4 88.62 576.07 664.69
1.5.3+mmap v3.9-rc3+mmap 1024 83.66 477.23 560.89
1.5.3+mmap v3.9-rc3+mmap 2048 83.44 477.21 560.65
1.5.3+mmap v3.9-rc3+mmap 10240 83.84 476.56 560.4

Did you calculate "Filter pages" by adding two [Excluding unnecessary
pages] lines? The first one of the two line is displayed by
get_num_dumpable_cyclic() during the calculation of the total number
of dumpable pages, which is later used to print progress of writing
pages in percentage.

For example, here is the log, where the number of cycles is 3, and

mem_map (16399)
mem_map : ffffea0801e00000
pfn_start : 20078000
pfn_end : 20080000
read /proc/vmcore with mmap()
STEP [Excluding unnecessary pages] : 13.703842 seconds<-- this part is by get_num_dumpable_cyclic()
STEP [Excluding unnecessary pages] : 13.842656 seconds
STEP [Excluding unnecessary pages] : 6.857910 seconds
STEP [Excluding unnecessary pages] : 13.554281 seconds<-- this part is by the main filtering processing.
STEP [Excluding unnecessary pages] : 14.103593 seconds
STEP [Excluding unnecessary pages] : 7.114239 seconds
STEP [Copying data ] : 138.442116 seconds
Writing erase info...
offset_eraseinfo: 1f4680e40, size_eraseinfo: 0

Original pages : 0x000000001ffc28a4
<cut>

So, get_num_dumpable_cyclic() actually does filtering operation but it
should not be included here.

If so, I guess each measured time would be about 42 seconds, right?
Then, it's almost same as the result I posted today: 35 seconds.

Yes, I added them together, the following is one dump message log:
<Log>
makedumpfile -c --message-level 23 -d 31 --map-size 10240 /proc/vmcore /sysroot/var/crash/vmcore_10240

cyclic buffer size has been changed: 77661798 => 77661184
Excluding unnecessary pages : [100 %] STEP [Excluding unnecessary pages] : 24.777717 seconds
Excluding unnecessary pages : [100 %] STEP [Excluding unnecessary pages] : 17.291935 seconds
Excluding unnecessary pages : [100 %] STEP [Excluding unnecessary pages] : 24.498559 seconds
Excluding unnecessary pages : [100 %] STEP [Excluding unnecessary pages] : 17.278414 seconds
Copying data : [100 %] STEP [Copying data ] : 476.563428 seconds


Original pages : 0x000000001ffe874d
Excluded pages : 0x000000001f79429e
Pages filled with zero : 0x00000000002b4c9c
Cache pages : 0x00000000000493bc
Cache pages + private : 0x00000000000011f3
User process data pages : 0x0000000000005c55
Free pages : 0x000000001f48f3fe
Hwpoison pages : 0x0000000000000000
Remaining pages : 0x00000000008544af
(The number of pages is reduced to 1%.)
Memory Hole : 0x000000001c0178b3
--------------------------------------------------
Total pages : 0x000000003c000000
</Log>


Thanks.
HATAYAMA, Daisuke



--
Thanks,
Jingbai Ma
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