On 01/07/2016 08:04 PM, Eric Blake wrote:
On 01/07/2016 06:55 AM, Denis V. Lunev wrote:
This series does three things:

1) add a "-trace [enable=]foo" option to enable one or more trace
events, and a "-trace help" option to show the list of tracepoints
(patches 4-5)

2) change the stderr tracing backend so that it prints to the
-D log file, and enable it by default.  "-trace file=..." is
now a synonym of -D if the log backend is enabled (patches 7-8)

3) add a "-d trace:foo" option that is a synonym for "-trace foo";
this makes the new functionality more discoverable to people used
to "-d", makes it available for user-mode emulation (which does
not have -trace), and is somewhat nice if you want to enable both
tracepoints and some other "-d" flag (patch 9).  When globbing
it is also less susceptible to unwanted shell expansion.

For example, you can trace block device I/O and save the result
to a file just by adding "-trace bdrv_aio_*,file=trace.txt", or
correlate it to guest PCs with "-d exec,nochain,trace:bdrv_aio_*".

Opinions?  I would like to have this in 2.5 if there is agreement.
Stale sentence :)

copy/paste forever :)

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