The following patches are a cleaned up version of the work Marios Kogias first posted in August. http://www.spinics.net/lists/ceph-devel/msg19890.html The changes are against Ceph 0.80.1, and will be moved forward soon. Changes since V1: * split build changes into separate patch * conditional build support for blkin (default off) * blkin is not a Ceph repo submodule build and install packages from https://github.com/agshew/blkin.git Note: rpms don't support babeltrace plugins for use with Zipkin * removal of debugging in Message::init_trace_info() With this patchset Ceph can use Blkin, a library created by Marios Kogias and others, which enables tracking a specific request from the time it enters the system at higher levels till it is finally served by RADOS. In general, Blkin implements the tracing semantics described in the Dapper paper http://static.googleusercontent.com/media/research.google.com/el/pubs/archive/36356.pdf in order to trace the causal relationships between the different processing phases that an IO request may trigger. The goal is an end-to-end visualisation of the request's route in the system, accompanied by information concerning latencies in each processing phase. Thanks to LTTng this can happen with a minimal overhead and in realtime. In order to visualize the results Blkin was integrated with Twitter's Zipkin http://twitter.github.io/zipkin/ (which is a tracing system entirely based on Dapper). In addition to cleanup, I've written a short document describing how to test Blkin tracing in Ceph (without Zipkin). See doc/dev/trace.rst In the immediate future I plan to: 1. push a wip-blkin branch to github.com/ceph and take advantage of gitbuilder test/qa 2. move the changes forward to ceph:master 3. submit a pull request 3. add Andreas' tracepoints https://github.com/ceph/ceph/pull/2877 using Blkin and investigate how easy it is to select the level of tracing detail -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
