[ltt-dev] [PATCH] Add time reduction option to synchronisation

[Benjamin Poirier]

On 14/09/10 07:24 PM, Masoume Jabbarifar wrote:
> There are two options to synchronise traces, accuracy and time that can be chosen
> by --sync-reduction in command line (something like --sync-reduction time)
> This algorithm finds excess links (when we synchronise A, B and A, C, we can be
> sure that we have synchronised B, C. But which link is excess? In this algorithm,
> the link that has less packet exchanges (less accuracy) has been removed so
> synchronisation time has been improved.
> In this patch, there are 55 trace files from 55 connected computers. This test
> data can help better understanding of two synchronisation algorithms.
>

The sync code is organized in a chain of modules and this code bypasses 
some of this modularization. I'm in the process of reviewing the patch 
and suggesting changes that could make it cleaner and keep the whole 
thing extensible. In the meantime, if you need a more pragmatic reason 
not to merge it, it crashes lttv:

$ ./runlttv -m eval -H gdb
[...]
Program received signal SIGSEGV, Segmentation fault.
0x0806eb64 in initMatchingTCP (syncState=0x8087b68) at 
sync/event_matching_tcp.c:118
118		if (syncState->reductionModule->preProcessReduction != NULL || 
syncState->stats) {

> Signed-off-by: Masoume Jabbarifar<masoume.jabbarifar at polymtl.ca>
> ---
>   lttv/lttv/Makefile.am                              |    2 +
>   lttv/lttv/sync/Makefile.am                         |    4 +-
>   lttv/lttv/sync/data_structures.c                   |    2 -
>   lttv/lttv/sync/event_matching_tcp.c                |   87 +++-
>   lttv/lttv/sync/event_matching_tcp.h                |    1 +

[mega snip]

Masoume, please read 
http://lxr.linux.no/#linux+v2.6.35.4/Documentation/SubmittingPatches, in 
particular section 8. That email was much too large. Besides, although 
the test data is interesting, I doubt it should reside in the source 
tree. You can instead provide a link to it in the "additional comments" 
section of the patch (see section 15).

-Ben