[PATCH 07/11] md: rewrite handle_stripe_dirtying6 in asynchronous way

[Yuri Tikhonov]

Hello Cheng,

On Friday, January 16, 2009 you wrote:

> Ack, could you please make the changelog more descriptive?
> and or add some of your benchmark results?

 Of course. We did benchmarking using the Xdd tool like follows:

# xdd -op write -kbytes $kbytes -reqsize $reqsize -dio-passes 2 –verbose -target $target_device

 where

$kbytes = data disks * size of disk
$reqsize= data disks * chunk size
$target_device = /dev/md0

 This way we did write of full array size, and thus achieved the 
maximum performance.

 The test cases were RAID-6 built on the top of 14 S-ATA drives 
connected to 2 LSI cards (7+7) inserted into the 800 MHz Katmai board 
(based on ppc440spe) equipped with 4GB of 800 MHz DRAM .

 Here are the results (Psw - write throughput with s/w RAID-6; Phw - 
write throughput with the h/w accelerated RAID-6):

 PAGE_SIZE=4KB, chunk=64/128/256 KB
        Psw = 71/72/74 MBps
        Phw = 128/136/139 MBps

 PAGE_SIZE=16KB, chunk=256/512/1024 KB
        Psw = 81/81/82 MBps
        Phw = 205/244/239 MBps

 PAGE_SIZE=64KB, chunk=1024/2048/4096 KB
        Psw = 84/84/85 MBps
        Phw = 258/253/258 MBps

 PAGE_SIZE=256KB, chunk=4096/8192/16384 KB
        Psw = 81/83/83 MBps
        Phw = 288/275/274 MBps

 Regards, Yuri

 --
 Yuri Tikhonov, Senior Software Engineer
 Emcraft Systems, www.emcraft.com