Hi -

alan wrote:

> [...] So its L1 misses more register reloads and the like. Sounds
> more and more like wasted clock cycles for debug. [...]

But it's not just "for debug"!  It is for system administrators,
end-users, developers.

> Its one thing to dump trace helper data into the kernel, its another
> when we all get to pay for it all the time when we don't need to
> [...]

Indeed, there will be some non-zero execution-time cost.  We must be
willing to pay *something* in order to enable this functionality.  One
question (still: http://lkml.org/lkml/2006/2/22/166) is trading
time/space cost; others include cross-platform vs. porting necessity;
robustness w.r.t. data-collectionand control-flow preservation.

- FChE