More on high i/o load wedging Fedora 10
sandeen at redhat.com
Wed Mar 18 15:15:14 UTC 2009
Robin Laing wrote:
> I always will report bugs if I can get the details. It is almost
> useless to report bugs if you don't have any details to post with it as
> there is a request for more details.
Thanks, I understand that.
> It takes time to learn what tools to use to find issues. I just read an
> IBM paper on tracing problems using iostat. I also found dstat at the
> same time. It is IO related as the problems all come from using or
> writing to a hard drive. It has also gotten worse and may be related to
> the latest kernel.
I understand, but in this thread I have repeatedly asked people hitting
this sort of hang to do "sysrq-w" (or, echo w > /proc/sysrq-trigger) -
nobody has ever shown me the results. 
I sympathize that it's hard to follow "this" thread, because it keeps
getting re-started under new subjects... :)
> My dumping EXT4 is more due to reports that I have read about data loss
> due to the procedure for write delays. I have run into the issue of
> losing my kde config files as reported by others on the net already.
patches are in Fedora already to mitigate this, it should not be a big
problem for you at this point. If it is, I need to know about it.
> I am also dumping EXT4 as I am trying to trace the issue with
> locking/freezing computer and I don't need data losses.
I understand; however, they may be related...
> As it stands, I did get a kernel oops last night that didn't crash my
> system and was logged in messages. I was using a tty session so this
> could be why the system didn't totally freeze.
> I have not had time to look through it and to see where it should be
> posted. It is related to USB as it occurred when I unplugged my USB
> drive that I was restoring data from. It was late and I was tired so I
> want to check things on the system before going further.
This may be something of a known issue, depending on the details. (a
drive disappearing should not actually *oops* the box, but it will
probably spew lots of warnings and errors at least.)
> There is an issue with filing kernel related bugs if the kernel is
> tainted because of Nvidia drivers. I have been told before that I need
> to remove the driver before filing a bug. Well that is hard to do when
> 3D is needed on the computer with the problem.
That's often true. Speaking for myself, if there is some weird behavior
never-before reported, and the kernel exhibiting that behavior has
binary modules loaded, I often won't dig into it much because TBH I
can't debug it 100%, and the binary module is always suspect. But if
the report correlates with other similar reports, it is still useful to
me, even with the binary module loaded.
> I just tried the sysrq 'w' but I don't have that command on my machine
> at work.
 I probably should have been more explicit when I asked for this.
# echo w > /proc/sysrq-trigger
# dmesg > dmesg_output.txt
should work on any fedora machine out of the box.
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