Re: [PATCH] btrfs file write debugging patch

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2011/3/1 Xin Zhong <thierryzhong@xxxxxxxxxxx>:
>
> Hi, Mitch
> I think you can config ftrace to just trace function calls of btrfs.ko which will save a lot of trace buffer space. See below command:
> #echo ':mod:btrfs' > /sys/kernel/debug/tracing/set_ftrace_filterAnd please send out the full ftrace log again.
>
> Another helpful information might be the strace log of the wmldbcreate process. It will show us the io pattern of this command.
> Thanks a lot for your help!
>
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I manually ran an strace around the build command (wmldbcreate) that
is causing my problem, and I am attaching the strace for that.

Please note that wmldbcreate does not seem to care when an error is
returned, and continues on.  So the error is occurring somewhat
silently in the middle, and isn't the last item.  The error is
probably associated with one of the 12288 byte writes.

I have re-run an ftrace following the conditions above, and have
hosted that file (~1.1MB compressed) on my local server at:

http://dontpanic.dyndns.org/trace-openmotif-btrfs-v15.gz

Please note I am still using some debugging modifications of my own to file.c.

They server the purpose of:
(1) Avoiding an infinite loop by identifying when the problem is
occuring, and exiting with error after 256 loops.
(2) Stopping the trace after exiting to keep from flooding the ftrace buffer.
(3) Provide debugging comments (all prefaced with "TPK:" in the trace).

Let me know if you want me to change any of the conditions.

Attachment: wmldbcreate-strace.gz
Description: GNU Zip compressed data


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