On Mon, Feb 02, 2004 at 05:57:16PM -0800, Jay Lessert wrote:
> On Mon, Feb 02, 2004 at 11:39:24PM +0100, Josef Wolf wrote:
> Just so you are aware, this is definitely not normal behavior (extreme
> system sluggishness during a single large file copy/move)!
Hmm..
> I assume you're running some flavor of linux. The usual suspect
> in that case is DMA not enabled on your IDE disk drive(s). Use
> hdparm to check. Don't let the man page scare you (too much):
>
> % sudo hdparm /dev/hda /dev/hdb
>
> ...is a safe thing to do. :-)
raven:~ # hdparm /dev/hda (this is the holding disk)
/dev/hda:
multcount = 16 (on)
IO_support = 1 (32-bit)
unmaskirq = 1 (on)
using_dma = 1 (on)
keepsettings = 0 (off)
readonly = 0 (off)
readahead = 8 (on)
geometry = 7297/255/63, sectors = 117231408, start = 0
raven:~ # hdparm /dev/hdd (this is the disk for the virtual tapes)
/dev/hdd:
multcount = 16 (on)
IO_support = 1 (32-bit)
unmaskirq = 1 (on)
using_dma = 1 (on)
keepsettings = 0 (off)
readonly = 0 (off)
readahead = 8 (on)
geometry = 2491/255/63, sectors = 40020624, start = 0
raven:~ # uname -a
Linux raven 2.4.21-166-athlon #1 Thu Dec 18 18:24:05 UTC 2003 i686 athlon
i386 GNU/Linux
raven:~ # head /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 6
model : 6
model name : AMD Athlon(tm) 4 Processor
stepping : 2
cpu MHz : 1394.065
cache size : 256 KB
fdiv_bug : no
hlt_bug : no
> Just a thought: one of the disks involved isn't an NFS mount, is it?
I don't use NFS.
> I made myself a 20GB file, and started a copy between two IDE
> disks on a relatively modest box:
> [ ... ]
> So that's about 26MB/s, not bad.
I tried with 4GB since I don't have that much free disk:
raven:/m/amchanger # time dd if=/dev/zero of=t bs=1024k count=4096
4096+0 records in
4096+0 records out
real 3m25.584s
user 0m0.031s
sys 0m15.144s
That's only 19MB/s. System slown a little bit down, but is still good usable
for interactive work.
raven:/m/amchanger # time cp t /m/spool/tmp/t
real 4m39.285s
user 0m0.398s
sys 0m25.867s
That's 14MB/s. Changing virtual desktops in kde lasts 20..30 seconds.
Pressing "UP" to access bash's history in kde's konsole lasts about 5..10
seconds.
This top output is on idle system:
top - 23:19:51 up 5 days, 12:08, 23 users, load average: 0.00, 0.08, 0.17
Tasks: 141 total, 1 running, 137 sleeping, 0 stopped, 3 zombie
Cpu(s): 1.9% user, 2.2% system, 0.0% nice, 95.9% idle
Mem: 514224k total, 475768k used, 38456k free, 50224k buffers
Swap: 0k total, 0k used, 0k free, 182920k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
4676 root 15 0 61376 19m 712 S 1.3 4.0 0:59.98 X
This one is when copying:
top - 23:22:41 up 5 days, 12:11, 24 users, load average: 2.86, 1.13, 0.54
Tasks: 143 total, 3 running, 137 sleeping, 0 stopped, 3 zombie
Cpu(s): 1.8% user, 22.5% system, 0.0% nice, 75.6% idle
Mem: 514224k total, 509680k used, 4544k free, 8456k buffers
Swap: 0k total, 0k used, 0k free, 275012k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
27744 root 16 0 88 88 24 R 12.5 0.0 0:14.56 cp
As you can see, "cached" goes up (the contents of the huge file get cached)
while "free" and "buffers" go down. Everything from "buffers" gets flushed.
The 182MB from "cached" get flushed and replaced with the contents from the
copied file as well.
I can't see anything interesting in the vmstat/iostat outputs, but I include
it here to be complete:
jw@raven:~> vmstat 5
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
2 2 0 4364 8312 277240 0 0 2 9 5 8 13 3 84 0
2 0 0 5116 7844 276964 0 0 19914 10231 1535 848 1 21 78 0
1 1 0 4708 8044 277172 0 0 18770 18381 1618 823 1 23 75 0
1 1 0 5340 8236 276348 0 0 19107 26817 1765 849 1 23 76 0
1 0 0 4380 8412 277132 0 0 19479 12169 1551 827 1 21 78 0
jw@raven:~> iostat 5
Linux 2.4.21-166-athlon (raven) 03.02.2004
avg-cpu: %user %nice %sys %idle
12,08 0,48 3,29 84,15
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
dev3-0 1,41 17,25 28,40 82084494 135164232
dev8-0 0,00 0,00 0,00 1530 0
dev8-1 0,00 0,00 0,00 1530 0
dev8-2 0,00 0,25 0,00 1211920 6196
dev8-3 0,00 0,00 0,00 1618 0
dev22-3 0,10 5,10 7,57 24279938 36054176
--
-- Josef Wolf -- jw AT raven.inka DOT de --
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