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SubjectRe: Unresponiveness of 2.4.16
Date
Am Mittwoch, 28. November 2001 03:34 schrieb Mike Fedyk:
> On Tue, Nov 27, 2001 at 06:13:41PM -0800, Andrew Morton wrote:
> > Dieter N?tzel wrote:
> > > Don't forget to tune max-readahead.
> >
> > Yes. Readahead is fairly critical and there may be additional fixes
> > needed in this area.
> >
> > Someone recently added the /proc/sys/vm/max_readahead (?) tunable.

-mt (Marcelo Tosatti) our _new_ 2.4.x maintainer did it.

> Isn't this part of the max-readahead patch?
>
> Does /proc/sys/vm/max_readahead affect scsi in any way?

Hello people, can you read?
I've reported U160 (SCSI) IBM DDYS (Ultrastar 36LZX) 18 GB 10k results...;-)

Kernel default:
SunWave1 src/linux# cat /proc/sys/vm/min-readahead
3
SunWave1 src/linux# cat /proc/sys/vm/max-readahead
31
SunWave1 src/linux# hdparm -tT /dev/sda1
/dev/sda1:
Timing buffer-cache reads: 128 MB in 0.80 seconds =160.00 MB/sec
Timing buffered disk reads: 64 MB in 2.28 seconds = 28.07 MB/sec


SunWave1 src/linux# cat /proc/sys/vm/max-readahead
127
SunWave1 src/linux# hdparm -tT /dev/sda1
/dev/sda1:
Timing buffer-cache reads: 128 MB in 0.80 seconds =160.00 MB/sec
Timing buffered disk reads: 64 MB in 1.87 seconds = 34.22 MB/sec

So it improved hdparm by 0.5 MB at the inner and 6 MB at the outer cylinders.

max-readahead=31 max-readahead=127
26-28 MB/s 26.5-34 MB/s

max-readahead=63 is nearly the same
max-readahead=255 little slower
max-readahead=511 even little slower

Here is a snipped of the IBM specs:

Performance
Data buffer 4 MB²
Rotational speed 10,000 RPM
Latency (average) 2.99 ms
Media transfer rate 280-452 Mbits/sec
Interface transfer rate 160 MB/sec
Sustained data rate 21.7- 36.1MB/sec

Seek time
Average 4.9 ms
Track to track 0.5 ms
Full track 10.5 ms

To Robert Love:
I get the following in dmesg:
lock-break-rml-2.4.16-1.patch

date: busy buffer
lock_break: buffer.c:681: count was 2 not 551
invalidate: busy buffer
lock_break: buffer.c:681: count was 2 not 551
invalidate: busy buffer
[-]

lock-break-rml-2.4.16-2.patch

validate: busy buffer
invalidate: busy buffer
invalidate: busy buffer
invalidate: busy buffer
[-]

Now my dbench numbers.
First without Noatun playing Ogg-Vorbis:
dbench/dbench> time ./dbench 32
32 clients started
........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................+................+..............................................................................+++.+.+.......+.....++++....++.....+++++.++++.++.+++++++********************************
Throughput 43.8254 MB/sec (NB=54.7818 MB/sec 438.254 MBit/sec)
14.490u 53.230s 1:37.40 69.5% 0+0k 0+0io 937pf+0w
system load: 23.52

Second Noatun playing Ogg-Vorbis (with hiccup):
dbench/dbench> time ./dbench 32
32 clients started
...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................+....+........................+.......++++...+.+...........+.+.....+++++.+.++..++..+++.++.++++.++********************************
Throughput 42.1212 MB/sec (NB=52.6515 MB/sec 421.212 MBit/sec)
14.710u 53.940s 1:41.29 67.7% 0+0k 0+0io 937pf+0w
system load: 26.30

Not bad, I think.
Andrew, your patch follows tomorrow.

Regards,
Dieter
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