Re: Implementing a generic binary trace interface.

[Martin Hunt <hunt at redhat dot com>]

On Thu, 2006-01-26 at 11:46 -0600, Jose R. Santos wrote:

> This sound like a good idea, but I wonder how it will perform compared 
> to gBTI.  For the purposes of trace, I think the best implementation is 
> the one with the best performance and smallest impact on the system.  If 
> we can get something like this to perform as good or better that gBTI 
> the is also a good candidate.  

The difference between the two is minor. gBTI passes in an integer that
is the number of 64-bit ints to log. 

_stp_binary_write(2, (int64_t)current->pid, (int64_t)current);

my proposal passes is a simple format string

_stp_trace("%2b%4b", current->pid, current)

There is a very small additional overhead involved in parsing that
format string. That should be offset by not always having to write 64-
bit binary values.

gBTI also defines a packet format to be used over the transport.
[seq-id][\0][num][arg1][arg2]....[arg(num-1)]

I am not doing that. Whatever program is processing the output just
needs to understand the format you write.

Martin