On 10.11.2012 09:55, Paolo Bonzini wrote:
Il 10/11/2012 09:30, Gerhard Wiesinger ha scritto:
2.) Added debug code to block.c and to block/vmdk.c to verify
correctness
Same here. Also, please use the tracing infrastructure---a lot of the
debug
messages you're adding, though not all, are in fact already available
(not
saying the others aren't useful!)
Any chance that the patch with debug code only (after some cleaning)
would be accepted (other modules do debug logging, too)?
I don't like to do useless work.
Tracing infrastructure is quite limited to function calls only (as far
as I saw).
No, tracing infrastructure uses function calls for tracing (messages go
into trace-events) but you can apply it to everything you want. Use the
stderr backend to debug it.
Tracing is a good thing for normal behavior but the major limitation is
that a function call must be involved. But for deep debugging one needs
a lot of more messages than function calls are available.
Of course every DPRINTF line could be made in a function call but IHMO
this introduces unnecessary overhead in performance.
So how to proceed further, some options:
1.) Add additional function calls for each DPRINTF statement?
2.) Add just plain DPRINTF statements?
3.) Or a mixture of both: on function call boundaries use Tracing, in
function debug info use DPRINTF?
4.) Refactor code that always function calls are involved?
Example:
static void traceing_func(int mul)
{
// Do nothing here
}
// Just some dummy useless function doing illustration
static int addandmultiply(int arg1, int arg2)
{
int mul = 0;
int sum = arg1 + arg2;
DPRINTF("....", arg1, arg2); // this one can be handled by tracing
infrastructure
DPRINTF("....", sum); // this one can't be done with tracing
if (sum == 0)
{
DPRINTF("sum=0"); // this one can't be done with tracing
return;
}
mul = arg1 * arg2;
DPRINTF(...., mul); // this one can't be done with tracing (except
with a introduced tracing function)
traceing_func(mul); // Introduce tracing function, performance penalty
return sum + mul;
}
So how to proceed further?
Ciao,
Gerhard
