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SubjectRe: UDMA 100 / PIIX4 question
On Mon, 19 Mar 2001 12:17:38 -0800
Tim Moore <timothymoore@bigfoot.com> wrote:

> Jeremy Jackson wrote:
> >
> > Tim Moore wrote:
> > > 15MB/s for hdparm is about right.
> >
> > Yes, since hdparm -t measures *SUSTAINED* transfers... the actual
> "head rate" of data reads from
> > disk surface. Only if you read *only* data that is alread in
> harddrive's cache will you get a speed
> > close to the UDMA mode of the drive/controller. The cache is around
> 1Mbyte, so for a split-second
> > re-read of some data....
>
> Apologies for the too brief answer. Sustained real world transfer rates
> for the PIIX4 under ideal
> setup conditions and a quiet bus are 14-18MB/s. Faster disk
> architecture and forcing ide driver
> parameters will not change this.
>
> Here's what you might expect from this disk family with an ATA-66
> capable chipset:
>
> [tim@abit tim]# hdparm -i /dev/hda; hdparm -tT /dev/hda
>
<snip>

> /dev/hda:
> Timing buffer-cache reads: 128 MB in 0.81 seconds =158.02 MB/sec
> Timing buffered disk reads: 64 MB in 1.85 seconds = 34.59 MB/sec
>
> Larger sustained transfers are about 75% of the burst/cache influenced
> hdparm timings.
>
> [tim@abit tim]# time dd if=/dev/hda of=/dev/null bs=1k count=500k
> 512000+0 records in
> 512000+0 records out
> 0.340u 6.780s 0:19.68 36.1% 0+0k 0+0io 115pf+0w
> [tim@abit tim]# echo "512000/19.68" | bc -q
> 26016
>

Hi,

First, many thanks to you both for responding (and Jerry for his further post mentioned below). Can I throw in the some actual figures just obtained on my system, and ask if these are consistent with what you are saying ?

cat /proc/ide/piix :

Intel PIIX4 Ultra 100 Chipset.
--------------- Primary Channel ---------------- Secondary Channel -------------
enabled enabled
--------------- drive0 --------- drive1 -------- drive0 ---------- drive1 ------
DMA enabled: yes no yes no
UDMA enabled: yes no yes no
UDMA enabled: 5 X 2 X
UDMA
DMA
PI

hdparm -tT /dev/hda :

/dev/hda:
Timing buffer-cache reads: 128 MB in 1.04 seconds =123.08 MB/sec
Timing buffered disk reads: 64 MB in 4.24 seconds = 15.09 MB/sec


time dd if=/dev/hda of=/dev/null bs=1k count=500k :
512000+0 records in
512000+0 records out

real 0m26.636s
user 0m0.220s
sys 0m8.190s


(d) bonnie -s 1000

---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*1000 10532 91.3 17757 11.3 6481 5.2 9604 71.1 20937 12.1 131.7 1.9


I had just written the above when the following post from Jeremy arrived :

"You should be able to get about 30 MB/s at the start of the disk (zone 0)
so if you were testing say /dev/hda1 which is at the start of the disk it should be faster.

Try hdparm -i /dev/hda (or whatever) .. . note the reported MaxMultSect= value,
and put it in place of X in command:

hdparm -u 1 -d 1 -m X -c 1 /dev/hda

Cheers,

Jeremy

PS - please let me know if this fixed your problem, since I have a system
with the same motherboard."

There is a Win partition - so I do not think I am at the start of the drive.

hdparm -i /dev/hda gives :

/dev/hda:

Model=IBM-DTLA-307030, FwRev=TX4OA50C, SerialNo=YKDYKLN6151
Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs }
RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=40
BuffType=3(DualPortCache), BuffSize=1916kB, MaxMultSect=16, MultSect=16
DblWordIO=no, OldPIO=2, DMA=yes, OldDMA=2
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=60036480
tDMA={min:120,rec:120}, DMA modes: mword0 mword1 mword2
IORDY=on/off, tPIO={min:240,w/IORDY:120}, PIO modes: mode3 mode4
UDMA modes: mode0 mode1 mode2 mode3 mode4 *mode5
Drive Supports : Reserved : ATA-2 ATA-3 ATA-4 ATA-5

I therefore tried hdparm -u 1 -d 1 -m 16 -c 1 -X69 /dev/hda :

/dev/hda:
setting 32-bit I/O support flag to 1
setting multcount to 16
setting unmaskirq to 1 (on)
setting using_dma to 1 (on)
setting xfermode to 69 (UltraDMA mode5)
multcount = 16 (on)
I/O support = 1 (32-bit)
unmaskirq = 1 (on)
using_dma = 1 (on)

Then hdparm -tT /dev/hda

/dev/hda:
Timing buffer-cache reads: 128 MB in 1.04 seconds =123.08 MB/sec
Timing buffered disk reads: 64 MB in 4.08 seconds = 15.69 MB/sec

These are, I fear, the figures I usually see.

Bed-time for Brits.

Regards,

Geoff

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