[PLUG] Time to downgrade?

Shridhar Daithankar ghodechhap at ghodechhap.net
Wed Jan 7 06:18:42 PST 2009


On Wednesday 07 January 2009 19:33:48 म.हा.सा.ग.र wrote:
> thanks for help from all...
>
> Here is a part of strace...
> =-=-=-=-=-=-=-=-=-=-=-=-=-
> read(10, 0x8dad2dc, 4096)               = -1 EAGAIN (Resource
> temporarily unavailable)
> clock_gettime(CLOCK_MONOTONIC, {12003, 477594114}) = 0
> clock_gettime(CLOCK_MONOTONIC, {12003, 477809225}) = 0
> clock_gettime(CLOCK_MONOTONIC, {12003, 477947791}) = 0
> clock_gettime(CLOCK_MONOTONIC, {12003, 478079092}) = 0
> read(10, 0x8dad2dc, 4096)               = -1 EAGAIN (Resource
> temporarily unavailable)
> poll([{fd=3, events=POLLIN}, {fd=11, events=POLLIN}, {fd=10,
> events=POLLIN}, {fd=6, events=POLLIN}, {fd=15, events=POLLIN}, {fd=20,
> events=POLLIN}, {fd=21, events=POLLIN}, {fd=18, events=POLLIN},
> {fd=23, events=POLLIN}, {fd=22, events=POLLIN}, {fd=27,
> events=POLLIN}, {fd=26, events=POLLIN}, {fd=19, events=POLLIN}], 13,
> 0) = 0
> clock_gettime(CLOCK_MONOTONIC, {12003, 478516857}) = 0
> read(10, 0x8dad2dc, 4096)               = -1 EAGAIN (Resource
> temporarily unavailable)
> clock_gettime(CLOCK_MONOTONIC, {12003, 478761581}) = 0
> read(10, 0x8dad2dc, 4096)               = -1 EAGAIN (Resource
> temporarily unavailable)
>
> =-=-=-=====-=-=-=-=-=-=-=-=

Hoping that the hang lasts for several seconds, rerun the strace, find the 
offending fd i.e. 10 in the above strace(first argument to the read, which is 
repeatedly unavailable) and see what file it is trying to open. 

You can dereference the fd -> file name in /proc/<pid>/fd directory.

> I am also wondering if this has got anything to do with *TSC clock
> source unstable*  message that i am getting for last few days...
> which maybe related to cmos battery?  But can that battery cause a
> problem when i am on M.S.E.D.C.L supply ?

Once the machine is booted, cmos battery doesn't come into play AFAIK. Its 
main job is to keep the clock running while the machine is off. When the 
machine is running linux, the OS keeps updating the time.

You could try syncing with a time server(which is as simple as running ntp 
client. No config required. Highly recommended.) Changing cmos battery is 
advised as well.

> anything else to look for?

Find the offending file. kmail is spending lot of time trying to read from it. 
It should give some clue. In my case, the fd 10 is a socket.(this is weird. I 
could not get any info. on what the other end of the socket is, even with lsof 
and netstat.)


-- 
 Shridhar



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