Dtrace LIO with new features is released

A new version of a nifty tool to dig into internals of logical IO by Alexander Anokhin and Andrey Nikolaev

Alexander Anokhin

What’s new in DTrace LIO?
Jump to introduction: Dynamic tracing of Oracle logical I/O

1. The list of supported functions performing logical I/O is extended:
Note: some function names below are my suggestions.

Consistent gets:

  • kcbgtcr – Kernel Cache Buffer Get Consistent Read. This is general entry point for consistent read.
  • kcbldrget – Kernel Cache Buffer Load Direct-Read Get. The function performing direct-path read. Interesting detail: 10.2 the function kcbldrget is called just after kcbgtcr, in 11.2 by (from) kcbgtcr.

Current gets (db block gets):

  • kcbgcur – Kernel Cache Buffer Get Current Read
  • kcbget – Kernel Cache Buffer Get Buffer. This is analogue of kcbgcur function, as I observed this function is called for index branch and leaf blocks
  • kcbnew – Kernel Cache Buffer New Buffer
  • kcblnb (kcblnb_dscn in 11.2) – Kernel Cache Buffer Load New Buffer. The function performing direct-path load. Decoding of block coordinates is not supported…

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