Difference: CmsIOInstrumenting (2 vs. 3)

Revision 32010-03-30 - BrianBockelman

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Instrumenting CMSSW I/O

This page discusses how to instrument CMSSW I/O at the Linux kernel in order to better understand how the application interacts with the block layer. The goals are:
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  1. User-level SystemTap tracing. Correlating between user-level events and kernel-level events.

Findings for CMSSW

  1. CMSSW with no cache. This is the out-of-the box behavior of CMSSW.
  1. CMSSW with readHint=application-only. This turns on TTreeCache, but does I/O in synchronous mode.
  2. CMSSW with readHint=storage-only. This turns on TTreeCache with I/O in asynchronous mode.
  1. CMSSW with the 2-cache scheme. This turns on the 2-cache scheme, as described by CmsIoWork2.
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