Re: DTrace syscall provider - please test/comment

[Matt Thomas <matt%3am-software.com@localhost>]

On Jun 25, 2013, at 5:25 AM, christos%zoulas.com@localhost (Christos Zoulas) 
wrote:

> On Jun 24,  6:12pm, matt%3am-software.com@localhost (Matt Thomas) wrote:
> -- Subject: Re: DTrace syscall provider - please test/comment
> 
> | 
> | On Jun 24, 2013, at 6:01 PM, Christos Zoulas 
> <christos%astron.com@localhost> wrote:
> | 
> | > Can't this be done as an addition/enhancement to the trace_enter()/
> | > trace_exit() facility instead of having to enter each syscall entry?
> | 
> | that only gets called if p->p_trace_enabled is set.  So now you need
> | a hook to set that on every lwp switch if the provider is tracing.
> 
> Right, and it (dtrace) can set a different (or the same flag) to enable
> it.


How does it set the same flag since that's per-proc and will need to changed
on context switch.  

A different flag is more overhead per syscall.