system hangs momentarily every 4 mins 2 secs

My system hangs momentarily every 4 mins 2 secs. The event coincides with
a 'top' entry in which 'events/0' grabs 50-95% of cpu capacity. How can I
determine what is causing the event?

Thanks,

Tom Arnall
north spit, ca

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Re: system hangs momentarily every 4 mins 2 secs

On Sat, 26 Aug 2006 12:55:33 -0700
tom arnall wrote:

> My system hangs momentarily every 4 mins 2 secs. The event coincides with
> a 'top' entry in which 'events/0' grabs 50-95% of cpu capacity. How can I
> determine what is causing the event?

First of all, I'm a newbie. But I'm interested in your subject.
What about trying 'pstree'

$ pstree -p

|--events/0(3)--|-aio/0(44)
|-kacpid(5)
|-kblockd/0(31)
|-khelper(4)
|-pdflush(41)
|-pdflush(42)


Then take the pid's and use top to monitor them.

$ top -p3,44,5,31,4,41,42

I don't know if the subtrees will show you anything, but maybe worth a try.

Mike

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Re: system hangs momentarily every 4 mins 2 secs

Hi,

On 8/27/06, mike@kevino.org wrote:
> On Sat, 26 Aug 2006 12:55:33 -0700
> tom arnall wrote:
>
> > My system hangs momentarily every 4 mins 2 secs. The event coincides with
> > a 'top' entry in which 'events/0' grabs 50-95% of cpu capacity. How can I
> > determine what is causing the event?

This is a long-shot but the last time I had the same problem it turned
out that there had developed a loose connection with the heat-sink and
processor on the motherboard.
As a result, the processor used to over-heat in about every 3 minutes
or so, the watchdogs would come into picture and cause the machine to
hang or reboot.... usually reboot.

Just give a quick check on your hardware before probing into the software side.


--
Raseel.
http://osd.byethost8.com
http://raseel.livejournal.com
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Re: system hangs momentarily every 4 mins 2 secs

On Saturday 26 August 2006 23:11, Raseel Bhagat wrote:
> Hi,
>
> On 8/27/06, mike@kevino.org wrote:
> > On Sat, 26 Aug 2006 12:55:33 -0700
> >
> > tom arnall wrote:
> > > My system hangs momentarily every 4 mins 2 secs. The event coincides
> > > with a 'top' entry in which 'events/0' grabs 50-95% of cpu capacity.
> > > How can I determine what is causing the event?
>
> This is a long-shot but the last time I had the same problem it turned
> out that there had developed a loose connection with the heat-sink and
> processor on the motherboard.
> As a result, the processor used to over-heat in about every 3 minutes
> or so, the watchdogs would come into picture and cause the machine to
> hang or reboot.... usually reboot.
>
> Just give a quick check on your hardware before probing into the software
> side.

how did you identify the problem with the heat sink?

is it likely that a hardware problem would cause the hanging phenomenon at
such a precise interval? i ran 'top' in batch mode to a file for ~.5 hour and
also wrote down the time whenever the hang occurred, then i compared the
output of top with the 'hang moments'. there was an exact coincidence
with 'top' entries in which 'events/0' was gobbling the cpu. and these events
occurred exactly 4 mins 2 secs from each other.

i also logged the content of /proc/interrupts at intervals of ~.2 sec's. in
this case, there was no change at the 'hang moments' except that i got only 1
sample for the second in which the hang occurred. in all other cases, of
course, i got 5 samples per second.

thanks in advance,

tom arnall
north spit, ca


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Re: system hangs momentarily every 4 mins 2 secs

tom arnall wrote:
> On Saturday 26 August 2006 23:11, Raseel Bhagat wrote:
>
>>Hi,
>>
>>On 8/27/06, mike@kevino.org wrote:
>>
>>>On Sat, 26 Aug 2006 12:55:33 -0700
>>>
>>>tom arnall wrote:
>>>
>>>>My system hangs momentarily every 4 mins 2 secs. The event coincides
>>>>with a 'top' entry in which 'events/0' grabs 50-95% of cpu capacity.
>>>>How can I determine what is causing the event?
>>
>>This is a long-shot but the last time I had the same problem it turned
>>out that there had developed a loose connection with the heat-sink and
>>processor on the motherboard.
>>As a result, the processor used to over-heat in about every 3 minutes
>>or so, the watchdogs would come into picture and cause the machine to
>>hang or reboot.... usually reboot.
>>
>>Just give a quick check on your hardware before probing into the software
>>side.
>
>
> how did you identify the problem with the heat sink?
>
> is it likely that a hardware problem would cause the hanging phenomenon at
> such a precise interval? i ran 'top' in batch mode to a file for ~.5 hour and
> also wrote down the time whenever the hang occurred, then i compared the
> output of top with the 'hang moments'. there was an exact coincidence
> with 'top' entries in which 'events/0' was gobbling the cpu. and these events
> occurred exactly 4 mins 2 secs from each other.
>
> i also logged the content of /proc/interrupts at intervals of ~.2 sec's. in
> this case, there was no change at the 'hang moments' except that i got only 1
> sample for the second in which the hang occurred. in all other cases, of
> course, i got 5 samples per second.
>
> thanks in advance,
>
> tom arnall
> north spit, ca

Tom -- You are right to be skeptical about the heat-sink suggestion.
I've had problems similar to that one, and they ALWAYS cause either a
reboot or a permanent hang (possibly with a kernel OOPS). They neve
cause the sort of transient problem you describe.

What you are seeing isn't really a "hang"; it is just the system
becoming busy with a task other than the one currently onscreen. The 2
seconds part intrigues me; might it be the case that the "hang" lasts
for 2 seconds? Or might the clock be 2 seconds off after it occurs?
(Hard to check from one instance, but over a day, this would lead to a
6-minute clock drift, easy to spot.)

I'm pretty sure "events" are what older kernels identify as keventd, a
process internal to the kernel. That is, you're seeing a line in top
something like this one ...

4 root 10 -5 0 0 0 S 0.0 0.0 0:00.00 events/0

.... except that the %CPU column is a lot higher.

If I'm right, and if you're using a 2.6.x kernel, then you might see if
the application systemTap will help you to diagnose the problem. You
might also check if any cron job is running on this 4-minute cycle.

The other obvious suspects here are device drivers. Does lsmod show
anything running that's out of the ordinary? Do you have WiFi running on
this system (if som using what deirvers)?

Finally, 50-95% is a pretty big range. It makes me wonder if there is
ALSO some process grabbing a lot of CPU (the other 50%, when this value
is low) on a regular basis. Do you see anything in top?

If none of this helps, and/or if any of my guesses have been wrong, you
might post again with a more complete description of the system, namely:
what distro and version, what kernel ("uname -a" usually is enough), and
what type and speed of CPU. The output of "free" is sometimes
instructive as well. And what is the typical system load (1.00 - the
"id" value as reported by top on its third line)?

Oh, and you you use this system for anything other than the usual sorts
of desktop and server uses?

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Re: system hangs momentarily every 4 mins 2 secs

On Saturday 26 August 2006 18:22, mike@kevino.org wrote:
> On Sat, 26 Aug 2006 12:55:33 -0700
>
> tom arnall wrote:
> > My system hangs momentarily every 4 mins 2 secs. The event coincides with
> > a 'top' entry in which 'events/0' grabs 50-95% of cpu capacity. How can I
> > determine what is causing the event?
>
> First of all, I'm a newbie. But I'm interested in your subject.
> What about trying 'pstree'
>
> $ pstree -p
>
>
> |--events/0(3)--|-aio/0(44)
> |
> |-kacpid(5)
> |-kblockd/0(31)
> |-khelper(4)
> |-pdflush(41)
> |-pdflush(42)
>
>
>
> Then take the pid's and use top to monitor them.
>
> $ top -p3,44,5,31,4,41,42
>
> I don't know if the subtrees will show you anything, but maybe worth a try.
>
> Mike

--
thanks,

tom arnall
north spit, ca
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another place where bootup messages are recorded?

Recently I have begun to get a great number of messages at boot-up which are
about 'querying' scsi drives. I need to get a better look at the messages,
but cannot find them in the logs in /var/log. Is there another place where
bootup messages are recorded?

Thanks,

Tom Arnall
north spit, ca




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Re: another place where bootup messages are recorded?

tom arnall wrote:

>Recently I have begun to get a great number of messages at boot-up which are
>about 'querying' scsi drives. I need to get a better look at the messages,
>but cannot find them in the logs in /var/log. Is there another place where
>bootup messages are recorded?
>
>Thanks,
>
>Tom Arnall
>north spit, ca
>
>
man dmesg
?
hth, Chuck

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Re: another place where bootup messages are recorded?

Chuck Gelm wrote:
> tom arnall wrote:
>
>> Recently I have begun to get a great number of messages at boot-up
>> which are about 'querying' scsi drives. I need to get a better look at
>> the messages, but cannot find them in the logs in /var/log. Is there
>> another place where bootup messages are recorded?
>>
>> Thanks,
>>
>> Tom Arnall
>> north spit, ca
>>
>>
> man dmesg
> ?
> hth, Chuck

In addition to what this man page tells you, see if you have a file
called /var/log/dmesg . Many (all?) distros these days dump the contents
of the dmesg buffer here during boot/init ... handy because dmesg
accesses a ring buffer, and later messages may have overwritten the
boot-time ones you want to see.

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Re: another place where bootup messages are recorded?

On Tuesday 29 August 2006 13:53, you wrote:
> On Tue, Aug 29, 2006 at 11:31:43AM -0700, tom arnall wrote:
> > Recently I have begun to get a great number of messages at boot-up which
> > are about 'querying' scsi drives. I need to get a better look at the
> > messages, but cannot find them in the logs in /var/log. Is there another
> > place where bootup messages are recorded?
>
> You'll have them printed by typing 'dmesg'
> Regards,
> Frederik
>


the messages aren't in there either ;( . the weird thing about them is they
say that the boot process is checking a scsi device, of which i have none on
my system. this phenomenon started btw after i installed the following:

suspend2
software to configure the touchpad
laptop mode
acpi-related stuff

also simultaneous to the appearance of the new messages was the appearance of
a recurring 'mini-hang' in the system. the hang lasts about one second and
occurs every 4 mins 2 secs exactly, except for a short period after booting,
when the intervals are smaller though still in a precise pattern. whenever
the hang occurs, the fan comes on for about 10 seconds.











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Re: system hangs momentarily every 4 mins 2 secs

On Wednesday 30 August 2006 13:50, John Kelly wrote:
> On Wed, 30 Aug 2006 14:35:12 -0700, tom arnall
>
> wrote:
> >Is there another place where bootup messages are recorded?
>
> Does your /etc/default/bootlogd say:
> > # Run bootlogd at startup ?
> > BOOTLOGD_ENABLE=yes
>
> That captures additional messages in /var/log/boot
>
> Be cautious though, if using a serial console. With bootlogd enabled,
> I had one system lock up at boot, when using a serial console.


thanks for the info. indeed it works: /var/log/boot has all the boot messages.

now for the messages of interest. i have been getting them as of ~1 month ago.
their appearance coincided with the appearance of another phenomenon: my
system momentarily hangs every 4 mins 2 secs exactly. by 'momentarily hangs'
i mean the CPU usage jumps to 50-99% usage (by events/0) and the system
doesn't respond to keyboard or mouse input. this lasts for about 1 second.
the messages are these, abbreviated somewhat:

Remounting filesystems.
/dev/hda1 not found in PARTITIONS.
/ not found in PARTITIONS.
Checking /dev/hda1 against HD because PARTITIONS contains "auto".
Considering /dev/hda.
/dev/hda1 contains /dev/hda, which is in HD, so we will remount it.
Considering /dev/hdb.
o
o
o
Considering /dev/sdg.
Considering /dev/sdh.
Original options: rw,notail
Reducing file system type.
No saved mount options, so apparently we never remounted this filesystem
during this session.
Not remounting.
Executing: blockdev --setra 256 /dev/hda1
proc not found in PARTITIONS.
/proc not found in PARTITIONS.
Checking proc against HD because PARTITIONS contains "auto".
Considering /dev/hda.
Considering /dev/hdb.
o
o
o
Considering /dev/sdf.
Considering /dev/sdg.
Considering /dev/sdh.
sysfs not found in PARTITIONS.
/sys not found in PARTITIONS.
Checking sysfs against HD because PARTITIONS contains "auto".
Considering /dev/hda.
Considering /dev/hdb.
o
o
o
Considering /dev/sdf.
Considering /dev/sdg.
Considering /dev/sdh.
devpts not found in PARTITIONS.
/dev/pts not found in PARTITIONS.
Checking devpts against HD because PARTITIONS contains "auto".
Considering /dev/hda.
Considering /dev/hdb.
o
o
o
Considering /dev/sdh.
tmpfs not found in PARTITIONS.
/dev/shm not found in PARTITIONS.
Checking tmpfs against HD because PARTITIONS contains "auto".
Considering /dev/hda.
Considering /dev/hdb.
o
o
o
Considering /dev/sdg.
Considering /dev/sdh.
usbfs not found in PARTITIONS.
/proc/bus/usb not found in PARTITIONS.
Checking usbfs against HD because PARTITIONS contains "auto".
Considering /dev/hda.
Considering /dev/hdb.
o
o
o
Considering /dev/sdg.
Considering /dev/sdh.
Setting spindown timeout on drives to 7200 seconds.
(hdparm configuration value = 244.)
Querying /dev/hda media type using device name: type 'disk' on bus 'ata'
detected
Querying /dev/hda media type using device name: type 'disk' on bus 'ata'
detected
Executing: hdparm -S 244 /dev/hda
/dev/hda: setting standby to 244 (2 hours)
Querying /dev/hdb media type using device name: failed - unknown name
Querying /dev/hdb type using hdparm: type 'disk' on bus 'ata' detected
Querying /dev/hdb media type using device name: failed - unknown name
Querying /dev/hdb type using hdparm: type 'disk' on bus 'ata' detected
Executing: hdparm -S 244 /dev/hdb
/dev/hdb: No such device or address
Querying /dev/hdc media type using device name: type 'cd' on bus 'ata'
detected
Skipping /dev/hdc: idle timeout control not supported.
Querying /dev/hdd media type using device name: failed - unknown name
o
o
o
Querying /dev/hdh media type using device name: failed - unknown name
Querying /dev/hdh type using hdparm: type 'disk' on bus 'ata' detected
Querying /dev/hdh media type using device name: failed - unknown name
Querying /dev/hdh type using hdparm: type 'disk' on bus 'ata' detected
Executing: hdparm -S 244 /dev/hdh
/dev/hdh: No such device or address
Querying /dev/sda media type using device name: type 'disk' on bus 'scsi'
detected
Querying /dev/sda media type using device name: type 'disk' on bus 'scsi'
detected
Executing: hdparm -S 244 /dev/sda
/dev/sda: No such device or address
Querying /dev/sdb media type using device name: type 'disk' on bus 'scsi'
detected
Querying /dev/sdb media type using device name: type 'disk' on bus 'scsi'
detected
Executing: hdparm -S 244 /dev/sdb
/dev/sdb: No such device or address
o
o
o
Querying /dev/sdg media type using device name: type 'disk' on bus 'scsi'
detected
Querying /dev/sdg media type using device name: type 'disk' on bus 'scsi'
detected
Executing: hdparm -S 244 /dev/sdg
/dev/sdg: No such device or address
Querying /dev/sdh media type using device name: type 'disk' on bus 'scsi'
detected
Querying /dev/sdh media type using device name: type 'disk' on bus 'scsi'
detected
Executing: hdparm -S 244 /dev/sdh
/dev/sdh: No such device or address

thanks in advance,

tom arnall
north spit, ca




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