Re: HEADS UP - major structure size changes in HEAD

[Aggelos Economopoulos <aoiko@xxxxxxxxxxxxxx>]

On 10/06/2010 05:16 πμ, Matthew Dillon wrote:
[...]
>      For the most part these tokens are not going to be held for more than
>      1uS or so, and often quite a bit less then that.  This is because
>      most kernel operations only take long periods of time because they
>      actually block, and of course the token will be released if the thread
>      blocks.
>
>      Take a vm_fault for example.  The fault occurs and then blocks on I/O.
>      That might be 200ns.  Then later on the I/O completes and the thread
>      wakes up and reacquires the token, then spends another 200ns with the
>      token held before returning from the fault.

I was thinking more about a soft pagefault, where you might need to 
search the VM data structures, do a few allocations and wait for an IPI 
roundtrip (for the pagetable invalidation).

Aggelos