LTTng tracing: ReplicatedPG::log_operation

[Andreas Bluemle <andreas.bluemle@itxperts.de>]

Hi,

during code profiling using LTTng, I encounter that during
processing of write requests to the cluster, the ceph-osd
spends a lot of time in the ReplicatedPG::log_operation
before the the actual writes to journal and object
in the FileStore are triggered.

This happens in ReplicatedBackend::submit_transaction.

What I wonder is
  - what is the purpose of the log_operation?
    If I am not mistaken, then it is neither the write-to-journal
    nor the write-to-object; both of these are triggered from 
    the queue_operation following that log_operation.

  - can the sequence between the log_operation and
    the actual queue_operation be reversed in
    ReplicatedBackend::submit_transaction?

   

Regards

Andreas Bluemle





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Andreas Bluemle                     mailto:Andreas.Bluemle@itxperts.de
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