Why systemtap loses events and what can be done about it?

[Mike Mason]

Frank Ch. Eigler wrote:
> Hi -
> 
> On Tue, Sep 04, 2007 at 12:29:34PM -0700, Mike Mason wrote:
> 

snip

>> Also, why do we only use per cpu variables for aggregations?  Is it
>> because of memory concerns or something more than that?
> 
> It's specifically not for memory concerns.  It's to increase available
> parallelism, with different CPUs *adding* data to aggregations
> concurrently with <<<.  (In contrast, *reading* data with @count
> etc. requires cross-cpu synchronization - modeled by exclusive locks -
> to produce meaningful data.)

Sorry, my question was unclear.  What I meant was "why don't we use per cpu variables for anything besides aggregations?"  I'm sure there's a good explanation (e.g. frequency and cost of cross-cpu synchronization too high).  I just want to understand how the design decision was made.

Mike

> 
> - FChE