Re: ATA RAID-0 FYI-Did the Impossible.

[Pavel Machek <pavel@suse.cz>]

Hi!

> TIOBENCH
> 
> No size specified, using 1792 MB
> Size is MB, BlkSz is Bytes, Read, Write, and Seeks are MB/sec
> 
>          File   Block  Num  Seq Read    Rand Read   Seq Write  Rand Write
>   Dir    Size   Size   Thr Rate (CPU%) Rate (CPU%) Rate (CPU%) Rate (CPU%)
> ------- ------ ------- --- ----------- ----------- ----------- -----------
>    .     1792   4096    1  153.6 98.1% 0.897 0.91% 85.59 51.2% 3.399 1.95%
>    .     1792   4096    2  104.7 67.8% 1.080 1.00% 79.63 58.4% 3.437 3.29%
>    .     1792   4096    4  91.57 61.2% 1.292 1.24% 76.45 59.3% 3.471 3.40%
>    .     1792   4096    8  83.55 57.3% 1.480 1.39% 73.80 59.2% 3.455 3.26%
> 
> 
> File './Bonnie.1089', size: 1073741824, volumes: 1
> Writing with putc()...  done:   9854 kB/s 100.0 %CPU
> Rewriting...            done:  65537 kB/s  52.2 %CPU
> Writing intelligently...done: 109124 kB/s  51.0 %CPU
> Reading with getc()...  done:   9821 kB/s  99.9 %CPU
> Reading intelligently...done: 167240 kB/s  97.6 %CPU
> Seeker 1...Seeker 2...Seeker 3...start 'em...done...done...done...
>               ---Sequential Output (nosync)--- ---Sequential Input-- --Rnd Seek-
>               -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --04k (03)-
> Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU   /sec %CPU
>        1*1024  9854 100.0 109124 51.0 65537 52.2  9821 99.9 167240 97.6 1504.4
> 6.4
> 
> hdparm -t /dev/md0
> 
> /dev/md0:
>  Timing buffered disk reads:  64 MB in  0.47 seconds =136.17 MB/sec
> 
> 
> hde: 39102336 sectors (20020 MB) w/2048KiB Cache, CHS=38792/16/63, UDMA(100)
> hdg: 39102336 sectors (20020 MB) w/2048KiB Cache, CHS=38792/16/63, UDMA(100)
> hdi: 39102336 sectors (20020 MB) w/2048KiB Cache, CHS=38792/16/63, UDMA(100)
> hdk: 39102336 sectors (20020 MB) w/2048KiB Cache, CHS=38792/16/63, UDMA(100)
> 
> /etc/raidtab
> 
> raiddev /dev/md0
>         raid-level              0
>         nr-raid-disks           4
>         persistent-superblock   0
>         chunk-size              <snipped>
> 
>         device                  /dev/hd<snipped>1
>         raid-disk               0
>         device                  /dev/hd<snipped>1
>         raid-disk               1
>         device                  /dev/hd<snipped>1
>         raid-disk               2
>         device                  /dev/hd<snipped>1
>         raid-disk               3
> 
> 
> If you want your system to have this kind of performance, that raise hell
> to get the patches adopted into the main kernel.

Raising hell is usually bad idea. What is so cool about that? You used
raid0, that means individual disk has 35MB/sec. That does not seem too
interesting to me.

And... you can have as fast system as you want. That will not help
your patches...
									Pavel
-- 
(about SSSCA) "I don't say this lightly.  However, I really think that the U.S.
no longer is classifiable as a democracy, but rather as a plutocracy." --hpa