Alan Cox wrote:
> On Gwe, 2006-02-10 at 18:02 +0200, Imre Gergely wrote:
>> maybe it's just me... but it looks like if as SCSI device the whole thing is
>> slower than with IDE. i haven't tested it yet, but as sda the system load is
>> very high, i did some tests with dd, and the CPU usage is always at 98-100%.
>
>
> Not expected behaviour. Can you provide hardware info and boot up
> messages please.
>
>
AMD Sempron 2600+, 512MB
00:09.0 IDE interface: nVidia Corporation MCP2A IDE (rev a3)
00:0b.0 IDE interface: nVidia Corporation nForce2 Serial ATA Controller (rev a3)
...
ata1: SATA max UDMA/133 cmd 0x9F0 ctl 0xBF2 bmdma 0xC800 irq 11
ata2: SATA max UDMA/133 cmd 0x970 ctl 0xB72 bmdma 0xC808 irq 11
input: ImPS/2 Generic Wheel Mouse on isa0060/serio1
ata1: dev 0 cfg 49:2f00 82:346b 83:7d01 84:4003 85:3468 86:3c01 87:4003 88:407f
ata1: dev 0 ATA, max UDMA/133, 312579695 sectors: lba48
nv_sata: Primary device added
nv_sata: Primary device removed
nv_sata: Secondary device removed
ata1: dev 0 configured for UDMA/133
scsi0 : sata_nv
ata2: no device found (phy stat 00000000)
scsi1 : sata_nv
Vendor: ATA Model: ST3160023AS Rev: 3.01
Type: Direct-Access ANSI SCSI revision: 05
SCSI device sda: 312579695 512-byte hdwr sectors (160041 MB)
SCSI device sda: drive cache: write back
SCSI device sda: 312579695 512-byte hdwr sectors (160041 MB)
SCSI device sda: drive cache: write back
sda: sda1 sda2 sda3 sda4
Attached scsi disk sda at scsi0, channel 0, id 0, lun 0
kjournald starting. Commit interval 5 seconds
...
[root@imi ~]# hdparm -tT /dev/sda
/dev/sda:
Timing cached reads: 1652 MB in 2.00 seconds = 825.95 MB/sec
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for
device
Timing buffered disk reads: 146 MB in 3.00 seconds = 48.60 MB/sec
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for
device
[root@imi stuff]# hdparm /dev/sda
/dev/sda:
IO_support = 0 (default 16-bit)
readonly = 0 (off)
readahead = 256 (on)
geometry = 19457/255/63, sectors = 160040803840, start = 0
[root@imi stuff]# cat /sys/block/sda/queue/scheduler
noop anticipatory deadline [cfq]
(but i tried all schedulers, didn't see any big improvements)
i tried to create an 1gb file like this:
[root@imi stuff]# time dd if=/dev/zero of=./1gbfile bs=512k count=2048
2048+0 records in
2048+0 records out
real 1m6.086s
user 0m0.012s
sys 0m5.920s
vmstat output lookes like this:
[root@imi ~]# vmstat 1
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
1 0 112 94208 1416 96616 0 0 762 427 933 3359 15 4 69 12
2 3 112 5076 808 180052 0 0 28 71260 768 3001 3 55 42 0
0 3 112 7060 820 178608 0 0 8 20500 632 2596 1 5 0 94
4 3 112 9292 820 178612 0 0 4 0 606 2695 1 1 0 98
0 2 112 6340 876 181740 0 0 16 22440 608 2689 1 49 0 50
0 2 112 5964 888 179848 0 0 20 54188 589 2761 5 25 0 70
0 2 112 7580 904 179900 0 0 40 0 583 2603 1 1 0 98
1 3 112 4956 932 182972 0 0 40 27404 622 2635 3 16 0 81
0 6 112 4952 952 182772 0 0 28 4000 664 2775 1 26 0 73
i read somewhere about some tests, SATA vs IDE, and they were talking about a
constant 10-13% CPU usage, nothing more.
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