Re: Linux Software RAID 5 Performance Optimizations: 2.6.19.1:(211MB/s read & 195MB/s write)

[Justin Piszcz]

On Fri, 12 Jan 2007, Michael Tokarev wrote:

> Justin Piszcz wrote:
> > Using 4 raptor 150s:
> > 
> > Without the tweaks, I get 111MB/s write and 87MB/s read.
> > With the tweaks, 195MB/s write and 211MB/s read.
> > 
> > Using kernel 2.6.19.1.
> > 
> > Without the tweaks and with the tweaks:
> > 
> > # Stripe tests:
> > echo 8192 > /sys/block/md3/md/stripe_cache_size
> > 
> > # DD TESTS [WRITE]
> > 
> > DEFAULT: (512K)
> > $ dd if=/dev/zero of=10gb.no.optimizations.out bs=1M count=10240
> > 10240+0 records in
> > 10240+0 records out
> > 10737418240 bytes (11 GB) copied, 96.6988 seconds, 111 MB/s
> []
> > 8192K READ AHEAD
> > $ dd if=10gb.16384k.stripe.out of=/dev/null bs=1M
> > 10240+0 records in
> > 10240+0 records out
> > 10737418240 bytes (11 GB) copied, 64.9454 seconds, 165 MB/s
> 
> What exactly are you measuring?  Linear read/write, like copying one
> device to another (or to /dev/null), in large chunks?
Check bonnie benchmarks below.
> 
> I don't think it's an interesting test.  Hint: how many times a day
> you plan to perform such a copy?
It is a measurement of raw performance.
> 
> (By the way, for a copy of one block device to another, try using
> O_DIRECT, with two dd processes doing the copy - one reading, and
> another writing - this way, you'll get best results without huge
> affect on other things running on the system.  Like this:
> 
>  dd if=/dev/onedev bs=1M iflag=direct |
>  dd of=/dev/twodev bs=1M oflag=direct
> )
Interesting, I will take this into consideration-- however, an untar test 
shows a 2:1 improvement, see below.
> 
> /mjt
> 

Decompress/unrar a DVD-sized file:

On the following RAID volumes with the same set of [4] 150GB raptors:

RAID  0] 1:13.16 elapsed @ 49% CPU
RAID  4] 2:05.85 elapsed @ 30% CPU 
RAID  5] 2:01.94 elapsed @ 32% CPU
RAID  6] 2:39.34 elapsed @ 24% CPU
RAID 10] 1:52.37 elapsed @ 32% CPU

RAID 5 Tweaked (8192 stripe_cache & 16384 setra/blockdev)::

RAID 5 TWEAKED: 1:06.41 elapsed @ 60% CPU

I did not tweak raid 0, but seeing how RAID5 tweaked is faster than RAID0 
is good enough for me :)

RAID0 did 278MB/s read and 317MB/s write (by the way)

Here are the bonnie results, the times alone speak for themselves, from 8 
minutes to min and 48-59 seconds.

# No optimizations:
# Run Benchmarks
Default Bonnie: 
[nr_requests=128,max_sectors_kb=512,stripe_cache_size=256,read_ahead=1536]
default_run1,4000M,42879,98,105436,19,41081,11,46277,96,87845,15,639.2,1,16:100000:16/64,380,4,29642,99,2990,18,469,5,11784,40,1712,12
default_run2,4000M,47145,99,108664,19,40931,11,46466,97,94158,16,634.8,0,16:100000:16/64,377,4,16990,56,2850,17,431,4,21066,71,1800,13
default_run3,4000M,43653,98,109063,19,40898,11,46447,97,97141,16,645.8,1,16:100000:16/64,373,4,22302,75,2793,16,420,4,16708,56,1794,13
default_run4,4000M,46485,98,110664,20,41102,11,46443,97,93616,16,631.3,1,16:100000:16/64,363,3,14484,49,2802,17,388,4,25532,86,1604,12
default_run5,4000M,43813,98,109800,19,41214,11,46457,97,92563,15,635.1,1,16:100000:16/64,376,4,28990,95,2827,17,388,4,22874,76,1817,13

169.88user 44.01system 8:02.98elapsed 44%CPU (0avgtext+0avgdata 
0maxresident)k
0inputs+0outputs (6major+1102minor)pagefaults 0swaps
161.60user 44.33system 7:53.14elapsed 43%CPU (0avgtext+0avgdata 
0maxresident)k
0inputs+0outputs (13major+1095minor)pagefaults 0swaps
166.64user 45.24system 8:00.07elapsed 44%CPU (0avgtext+0avgdata 
0maxresident)k
0inputs+0outputs (13major+1096minor)pagefaults 0swaps
161.90user 44.66system 8:00.85elapsed 42%CPU (0avgtext+0avgdata 
0maxresident)k
0inputs+0outputs (13major+1094minor)pagefaults 0swaps
167.61user 44.12system 8:03.26elapsed 43%CPU (0avgtext+0avgdata 
0maxresident)k
0inputs+0outputs (13major+1092minor)pagefaults 0swaps


All optimizations [bonnie++] 

168.08user 46.05system 5:55.13elapsed 60%CPU (0avgtext+0avgdata 
0maxresident)k
0inputs+0outputs (16major+1092minor)pagefaults 0swaps
162.65user 46.21system 5:48.47elapsed 59%CPU (0avgtext+0avgdata 
0maxresident)k
0inputs+0outputs (7major+1101minor)pagefaults 0swaps
168.06user 45.74system 5:59.84elapsed 59%CPU (0avgtext+0avgdata 
0maxresident)k
0inputs+0outputs (7major+1102minor)pagefaults 0swaps
168.00user 46.18system 5:58.77elapsed 59%CPU (0avgtext+0avgdata 
0maxresident)k
0inputs+0outputs (13major+1095minor)pagefaults 0swaps
167.98user 45.53system 5:56.49elapsed 59%CPU (0avgtext+0avgdata 
0maxresident)k
0inputs+0outputs (5major+1101minor)pagefaults 0swaps

c6300-optimized:4000M,43976,99,167209,29,73109,22,43471,91,208572,40,511.4,1,16:100000:16/64,1109,12,26948,89,2469,14,1051,11,29037,97,2167,16
c6300-optimized:4000M,47455,99,190212,35,70402,21,43167,92,206290,40,503.3,1,16:100000:16/64,1071,11,29893,99,2804,16,1059,12,24887,84,2090,16
c6300-optimized:4000M,43979,99,172543,29,71811,21,41760,87,201870,39,498.9,1,16:100000:16/64,1042,11,30276,99,2800,16,1063,12,29491,99,2257,17
c6300-optimized:4000M,43824,98,164585,29,73470,22,43098,90,207003,40,489.1,1,16:100000:16/64,1045,11,30288,98,2512,15,1018,11,27365,92,2097,16
c6300-optimized:4000M,44003,99,194250,32,71055,21,43327,91,196553,38,505.8,1,16:100000:16/64,1031,11,30278,98,2474,14,1049,12,28068,94,2027,15

txt version of optimized results:

Version  1.03      ------Sequential Output------ --Sequential Input- 
--Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- 
--Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  
/sec %CP
c6300-optimiz 47455    99 190212    35 70402    21 43167    92 206290    
40 503.3     1
c6300-optimiz 43979    99 172543    29 71811    21 41760    87 201870    
39 498.9     1
c6300-optimiz 43824    98 164585    29 73470    22 43098    90 207003    
40 489.1     1
c6300-optimiz 44003    99 194250    32 71055    21 43327    91 196553    
38 505.8     1

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