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Old 04-26-2013, 09:07 AM   #1
zcool
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Question Memset & memcpy extremly slow on E5-2420


Hello,

I'm benchmarking our new Supermicro servers and i noticed poor performances of the memset and memcpy fonctions

The config : 2x E5-2420, 12 x 8Gb DDR3 ECC reg 12800, SSD , debian stable amd64 up to date

Stream results are really good :
Function Best Rate MB/s Avg time Min time Max time
Copy: 35890.9 0.004463 0.004458 0.004470
Scale: 35715.2 0.004493 0.004480 0.004531
Add: 36412.8 0.006597 0.006591 0.006601
Triad: 36535.7 0.006580 0.006569 0.006588

but bandwidth-0.32 is giving me poor library performances :
Library: memset 3991.9 MB/s
Library: memcpy 2373.5 MB/s


If i compare with our development server Dell R210 server ( 1 x E31240, 4 x 4 GB DDR3 1333, sata 10k, debian stable amd64 up to date),
stream is much slower :
Function Best Rate MB/s Avg time Min time Max time
Copy: 11862.3 0.023112 0.013488 0.043449
Scale: 11829.9 0.022943 0.013525 0.034822
Add: 13162.2 0.024458 0.018234 0.034396
Triad: 13263.3 0.026572 0.018095 0.036060


but, in use, memset and memcpy are really faster :
Library: memset 15411.6 MB/s
Library: memcpy 7925.9 MB/s


Is there something i can do ?

What could be the reason of the poor performances of Supermicro ?

Thank's a lot for help !
 
Old 04-27-2013, 03:16 AM   #2
pan64
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have you tried another tool also? there is a comment on http://zsmith.co/bandwidth.html: Be nice On Linux, I recommend using nice -n -2 when running bandwidth. The kernel may attempt to throttle the process otherwise.
Have you checked it?
 
Old 04-29-2013, 05:55 AM   #3
zcool
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Question others tests

Thanks for the help.

Tryed with nice but changed nothing

I tested with mbw :
Long uses 8 bytes. Allocating 2*134217728 elements = 2147483648 bytes of memory.
Using 262144 bytes as blocks for memcpy block copy test.
Getting down to business... Doing 1 runs per test.
0 Method: MEMCPY Elapsed: 0.24884 MiB: 1024.00000 Copy: 4115.061 MiB/s
AVG Method: MEMCPY Elapsed: 0.24884 MiB: 1024.00000 Copy: 4115.061 MiB/s
0 Method: DUMB Elapsed: 0.43245 MiB: 1024.00000 Copy: 2367.876 MiB/s
AVG Method: DUMB Elapsed: 0.43245 MiB: 1024.00000 Copy: 2367.876 MiB/s
0 Method: MCBLOCK Elapsed: 0.13020 MiB: 1024.00000 Copy: 7865.125 MiB/s
AVG Method: MCBLOCK Elapsed: 0.13020 MiB: 1024.00000 Copy: 7865.125 MiB/s

and compared with dell r210 :
Long uses 8 bytes. Allocating 2*134217728 elements = 2147483648 bytes of memory.
Using 262144 bytes as blocks for memcpy block copy test.
Getting down to business... Doing 1 runs per test.
0 Method: MEMCPY Elapsed: 0.18472 MiB: 1024.00000 Copy: 5543.645 MiB/s
AVG Method: MEMCPY Elapsed: 0.18472 MiB: 1024.00000 Copy: 5543.645 MiB/s
0 Method: DUMB Elapsed: 0.12824 MiB: 1024.00000 Copy: 7985.277 MiB/s
AVG Method: DUMB Elapsed: 0.12824 MiB: 1024.00000 Copy: 7985.277 MiB/s
0 Method: MCBLOCK Elapsed: 0.06777 MiB: 1024.00000 Copy: 15110.377 MiB/s
AVG Method: MCBLOCK Elapsed: 0.06777 MiB: 1024.00000 Copy: 15110.377 MiB/s



If i compare cached reads from hdparm, i have the same problem :
Supermicro :
sudo hdparm -tT /dev/sda

/dev/sda:
Timing cached reads: 13684 MB in 2.00 seconds = 6850.07 MB/sec
Timing buffered disk reads: 1152 MB in 3.00 seconds = 383.49 MB/sec


Dell:
sudo hdparm -tT /dev/sda

/dev/sda:
Timing cached reads: 24470 MB in 2.00 seconds = 12250.99 MB/sec
Timing buffered disk reads: 368 MB in 3.01 seconds = 122.35 MB/sec


I designed this server for large scale database server but theses memory bandwidth problems give me poor cached hits performances.
On mysql benchmarks, 900 dell r210 is twice better than 4000 supermicro ...

I'm very disappointed...
 
  


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