[Bug translator/9931] New: diagnostic aids for module cache collisions

[Bug translator/9931] New: diagnostic aids for module cache collisions

[fche at redhat dot com]

We seem to encounter occasional module cache hash collisions.
In order to diagnose these better, we should track some more
information, such as a log file in ../cache itself to record
something about the context & versions.  Maybe even log some
substrings of the hash.cxx::hash() parameters.

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           Summary: diagnostic aids for module cache collisions
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: translator
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: fche at redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=9931

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[Bug translator/9931] diagnostic aids for module cache collisions

[wenji dot huang at oracle dot com]

------- Additional Comments From wenji dot huang at oracle dot com  2010-01-29 08:21 -------
Created an attachment (id=4564)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=4564&action=view)
Draft patch

Initialize implementation of a simple log file to record
every hash operation.

ash log file :
/home/wjhuang/.systemtap/stap_hash.log

[Wed Jan 27 11:13:21 2010]tracequery_hash:
2.6.33-rc5,i386,/lib/modules/2.6.33-rc5/build,/lib/modules/2.6.33-rc5/build/include/trace/syscall.h

result:f5608c4e210b53ab1591419c1dd54a88_457
[Wed Jan 27 11:13:28 2010]stapconf_hash:
2.6.33-rc5,i386,/lib/modules/2.6.33-rc5/build
result:cb130f7753fed3a69399b43d434e7bce_396
[Wed Jan 27 11:13:28 2010]script_hash:
2.6.33-rc5,i386,-b,-t,'kernel.function("sys_open@fs/open.c:107...'
result:95d439ce01faad6a5cb1076009382839_2012

-- 


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[Bug translator/9931] diagnostic aids for module cache collisions

[fche at redhat dot com]

------- Additional Comments From fche at redhat dot com  2010-01-29 17:50 -------
Thanks for the draft.  Two ideas to consider:
- extending the hash.add() function to pass names along with the 
  hash-mix values, so that class hash can internally track the
  hash-report string
- storing the reports themselves in the cache, beside the .ko / .c
  files, and changing the cache-size-limit logic to delete
  these .txt files upon garbage collection


-- 


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[Bug translator/9931] diagnostic aids for module cache collisions

[wenji dot huang at oracle dot com]

------- Additional Comments From wenji dot huang at oracle dot com  2010-02-02 09:31 -------
Created an attachment (id=4568)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=4568&action=view)
Patch v2

Revamp patch to address frank's concern.

1. Keep all the parameters in hash::add and store them with hash result.

2. The log file will be generated at the end of find_*_hash function, and
   put at the same directory as *.ko.

3. Update cache-mb-limit so as to remove the log file once cache reaches
   limitation.

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           What    |Removed                     |Added
----------------------------------------------------------------------------
Attachment #4564 is|0                           |1
           obsolete|                            |


http://sourceware.org/bugzilla/show_bug.cgi?id=9931

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[Bug translator/9931] diagnostic aids for module cache collisions

[wenji dot huang at oracle dot com]

------- Additional Comments From wenji dot huang at oracle dot com  2010-02-03 02:39 -------
commit	0d1ad607311857dc0b4666ce8a84c1a59c615ab9

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[Bug translator/9931] diagnostic aids for module cache collisions

[fche at redhat dot com]

------- Additional Comments From fche at redhat dot com  2010-02-03 12:32 -------
committed

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://sourceware.org/bugzilla/show_bug.cgi?id=9931

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