Re: [PATCH 2/2] proc: Add /proc/<pid>/timerslack_ns interface

[John Stultz]

On Thu, Jul 14, 2016 at 6:42 AM, Arjan van de Ven <arjan@xxxxxxxxxxxxxxx> wrote:
> On 7/14/2016 5:48 AM, Serge E. Hallyn wrote:
>
>> Can someone give a detailed explanation of what you could do with
>> the new timerslack feature and compare it to what you can do with
>> sys_nice?
>>
>
> what you can do with the timerslack feature is add upto 4 seconds of extra
> time/delay on top of each select()/poll()/nanosleep()/... (basically
> anything that
> uses hrtimers on behalf of the user), and then also control within that
> 4 second window exactly when that extra delay ends
> (which may help a timing attack kind of scenario)

So the interface actually allows for 64bits of nanoseconds, so more or
less infinite delay if nothing else is happening.

thanks
-john