Commit 07ce9e52 authored by Alessandro Rubini's avatar Alessandro Rubini

doc: documented drop support

Signed-off-by: Alessandro Rubini's avatarAlessandro Rubini <rubini@gnudd.com>
parent d16ddc1a
......@@ -35,7 +35,7 @@
@setchapternewpage off
@set update-month March 2014
@set update-month July 2014
@set release __RELEASE_GIT_ID__
@finalout
......@@ -427,11 +427,56 @@ may document the keywords, if the time allows it.
configuration options. This applies to the priorities, intervals and
thresholds, as well as the @i{slave-only} flag.
@c ==========================================================================
@node Configuring Faults
@section Configuring Faults
Configuration, for @t{arch-unix} and @t{arch-wrs}, allows to provide
some fault injection.
In particular, the program allows dropping frames, in both the TX and RX
paths. The configuration values state how many frames are dropped every
1000. Dropping is randomized, but the user can set the seed to ensure
a repeatable dropping sequence.
Dropping transmitted frames is performed by reporting success (and the
timestamp), while no frame is actually sent. A diagnostic message
is generated at @t{frames} level 1, but other than than that nothing
happens. Actually, @t{arch-wrs} needs to actually send a frame in
order to get a timestamp back; in this case the program modifies the
frame, to use a wrong Ethernet type or a wrong UDP port.
Dropping received frames is performed by actually receiving (and
timestamping), but returning a special error code to the caller.
Again, PPSi creates a diagnostic message at @t{frames} level 1.
The following configuration lines are supported:
@table @code
@item rx-drop <value>
@itemx tx-drop <value>
Drop @i{value} frames every 1000 frames received or sent.
The randomized sequence is global.
@end table
The randomization see can be passed by pre-setting the environment
variable @t{PPSI_DROP_SEED} to a decimal numeric value. For example:
@smallexample
export PPSI_DROP_SEED=33
@end smallexample
@noindent
before starting the daemon.
@c ==========================================================================
@node Configuring the Simulator
@section Configuring the Simulator
To tun the PPSi simulator you need to rely on diagnostics and specific
To run the PPSi simulator you need to rely on diagnostics and specific
configuration items. The configuration items are defined in
@i{arch-sim/sim-conf.c} and are not individually documented here at
this point.
......
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