在red hat linux 7.2下如何開啟DMA ???

[jollinman]

因為每次取讀硬碟資料的時候...
cpu資源就佔到100%
偏偏我這ibm硬碟的效能實在是..
所以我突然想到如果開啟DMA的話效能一定有顯著的提升

其實還有個解決方法...
我這裡有IDE TO SCSI 的轉卡
cpu使用率會在10%以下
但是因為有些東西會發生確認上的問題
(畢竟不是原本的介面阿...)
所以我請教一下設定的方法
謝謝~!!

[repsol]

man hdparm



NAME
hdparm - get/set hard disk parameters

SYNOPSIS
hdparm [ -a [sectcount] ] [ -A [0|1] ] [ -c [chipset_mode]
] [ -C ] [ -d [0|1] ] [ -f ] [ -g ] [ -i ] [ -k [0|1] ] [
-K [0|1] ] [ -L [0|1] ] [ -m [sectcount] ] [ -p
[0|1|2|3|4|5] ] [ -P [sectcount] ] [ -q ] [ -r [0|1] ] [
-S [timeout] ] [ -T ] [ -t ] [ -u [0|1] ] [ -v ] [ -W
[0|1] ] [ -X [xfermode] ] [ -y ] [ -Y ] [ -Z ] [device] ..



............... 略刪..........................................................



-d


Disable/enable the "using_dma" flag for this drive.
This option only works with a few combinations of
drives and interfaces which support DMA and which
are known to the IDE driver (and with all supported
XT interfaces). In particular, the Intel Triton
chipset is supported for bus-mastered DMA operation
with many drives (experimental). It is also a good
idea to use the -X34 option in combination with -d1
to ensure that the drive itself is programmed for
multiword DMA mode2. Using DMA does not necessarily
provide any improvement in throughput or system
performance, but many folks swear by it. Your
mileage may vary.

............... 略刪..........................................................


-X


Set the IDE transfer mode for newer (E)IDE/ATA2
drives. This is typically used in combination with
-d1 when enabling DMA to/from a drive on a sup-
ported interface chipset (such as the Intel 430FX
Triton), where -X34 is used to select multiword DMA
mode2 transfers. With systems which support Ultra-
DMA burst timings, -X66 is used to select UltraDMA
mode2 transfers (you'll need to prepare the chipset
for UltraDMA beforehand). Apart from that, use of
this flag is seldom necessary since most/all modern
IDE drives default to their fastest PIO transfer
mode at power-on. Fiddling with this can be both
needless and risky. On drives which support transfer modes,
-X can be used to switch the mode of the drive only.
Prior to changing the transfer mode, the IDE interface
should be jumpered or programmed (see -p flag) for the new
mode set?
ting to prevent loss and/or corruption of data.
Use this with extreme caution! For the PIO (Programmed
Input/Output) transfer modes used by Linux,
this value is simply the desired PIO mode number
plus 8. Thus, a value of 09 sets PIO mode1, 10
enables PIO mode2, and 11 selects PIO mode3. Setting 00
restores the drive's "default" PIO mode,
and 01 disables IORDY. For multiword DMA, the
value used is the desired DMA mode number plus 32.
for UltraDMA, the value is the desired UltraDMA
mode number plus 64.



上面抓出比較重要的參數...希望對你有幫助

記的改完之後...要把這串命令放在開機會自動執行的地方 /etc/rc2.d/.../etc/rc3.d/??
要不然重開機...這樣的設定就沒效了..

[iget]

或是參考linuxfab.cx
http://www.linuxfab.cx/indexColumnDa...=72&FIRSTHIT=1

[jollinman]

/dev/hda: No such device or address

我硬碟設jump為slve..............

結論...失敗............@@"