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Why are the MB/s of avx and raid6: twice as high for a docked ThinkPad than for an undocked ?

DISCUSSION Toralf Förster 2 participants 3 messages Jun 15, 2016 – Jun 16, 2016

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Toralf Förster

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#0 lore raw

This diff is reliable depending whether the T440s is docked (right) or not (left) :

Linux t44 4.5.7-hardened-r2 #1 SMP Wed Jun 15 23:39:10 CEST 2016 x86_64 Intel(R) Core(TM) i5-4300U CPU @ 1.90GHz GenuineIntel GNU/Linux

215c215
< avx : 10196.000 MB/sec
---

Quoted 1 line
   avx       : 23504.000 MB/sec

225,234c225,234

< raid6: sse2x1   gen()  2578 MB/s
< raid6: sse2x1   xor()  2007 MB/s
< raid6: sse2x2   gen()  3246 MB/s
< raid6: sse2x2   xor()  2203 MB/s
< raid6: sse2x4   gen()  3773 MB/s
< raid6: sse2x4   xor()  2640 MB/s
< raid6: avx2x1   gen()  5042 MB/s
< raid6: avx2x2   gen()  5812 MB/s
< raid6: avx2x4   gen()  6824 MB/s

< raid6: using algorithm avx2x4 gen() 6824 MB/s
---

Quoted 10 lines

raid6: sse2x1 gen() 5816 MB/s
raid6: sse2x1 xor() 4515 MB/s
raid6: sse2x2 gen() 7261 MB/s
raid6: sse2x2 xor() 4968 MB/s
raid6: sse2x4 gen() 8511 MB/s
raid6: sse2x4 xor() 5916 MB/s
raid6: avx2x1 gen() 11378 MB/s
raid6: avx2x2 gen() 13117 MB/s
raid6: avx2x4 gen() 15398 MB/s
raid6: using algorithm avx2x4 gen() 15398 MB/s

And why do the units differ (MB/sec versus MB/s) ?

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Toralf
PGP: C4EACDDE 0076E94E, OTR: 420E74C8 30246EE7
#1 lore raw
Quoted 18 lines · Toralf Förster

This diff is reliable depending whether the T440s is docked (right) or not (left) :

Linux t44 4.5.7-hardened-r2 #1 SMP Wed Jun 15 23:39:10 CEST 2016 x86_64 Intel(R) Core(TM) i5-4300U CPU @ 1.90GHz GenuineIntel GNU/Linux

215c215
< avx : 10196.000 MB/sec
---

Quoted 1 line
   avx       : 23504.000 MB/sec

225,234c225,234

< raid6: sse2x1   gen()  2578 MB/s
< raid6: sse2x1   xor()  2007 MB/s
< raid6: sse2x2   gen()  3246 MB/s
< raid6: sse2x2   xor()  2203 MB/s
< raid6: sse2x4   gen()  3773 MB/s
< raid6: sse2x4   xor()  2640 MB/s
< raid6: avx2x1   gen()  5042 MB/s
< raid6: avx2x2   gen()  5812 MB/s
< raid6: avx2x4   gen()  6824 MB/s
Quoted 12 lines

< raid6: using algorithm avx2x4 gen() 6824 MB/s
---

Quoted 10 lines

raid6: sse2x1 gen() 5816 MB/s
raid6: sse2x1 xor() 4515 MB/s
raid6: sse2x2 gen() 7261 MB/s
raid6: sse2x2 xor() 4968 MB/s
raid6: sse2x4 gen() 8511 MB/s
raid6: sse2x4 xor() 5916 MB/s
raid6: avx2x1 gen() 11378 MB/s
raid6: avx2x2 gen() 13117 MB/s
raid6: avx2x4 gen() 15398 MB/s
raid6: using algorithm avx2x4 gen() 15398 MB/s

Did you try setting the BIOS to "highest performance" mode even while on battery?

BTW: update the BIOS of the T440s if you haven't done so already, AFAIK there are some nasties in the outdated microcode and right now the only way to get the fixed microcode for these processors is through a BIOS update. Latest BIOS for the T440s is from 2016-04-27.

Quoted 1 line

And why do the units differ (MB/sec versus MB/s) ?

For the typical "no good reason at all".

The proper SI units for these are actually "MiB/s", I think: AFAIK, the kernel is measuring base-2 throughput, not base-10 throughput...

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  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh
author
#2 lore raw
Quoted 2 lines · Henrique de Moraes Holschuh

Did you try setting the BIOS to "highest performance" mode even while on battery?

ough - that was it - *head smack*

Quoted 1 line

BTW: update the BIOS of the T440s if you haven't done so already, AFAIK

did it

Thx Henrique for the answer

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Toralf
PGP: C4EACDDE 0076E94E, OTR: 420E74C8 30246EE7