Questions about STP_TIMING

[Vara Prasad]

Frank Ch. Eigler wrote:

>Hi -
>
>On Thu, Jan 25, 2007 at 03:04:37PM -0800, Stone, Joshua I wrote:
>  
>
>>I have a couple of questions about STP_TIMING.  First, why are the cycle
>>counts truncated to 32-bits?  [...]
>>    
>>
>
>This was my doing, in response to learning someplace that some popular
>processors' cycle counters are relatively short before wrapping -
>longer than 32 bits but shorter than 64.  Since individual probe
>handlers tend to run for much shorter intervals than billions of
>cycles, 32 seemed like a good general compromise.
>
>When/if we start supporting non-atomic probe handlers, then this part
>will need to be revisited, for example since the "less than billions
>of cycles" assumption will become invalid.
>
>  
>
I interpret your atomic probe handlers mean the handler that runs 
without sleeping/pre-emption to completion. User space probes handlers 
can sleep (Jim correct me if i am wrong). This may be one of the things 
we have to revisit when we start supporting uprobes.

bye,
Vara Prasad
[snip]