lkml.org 
[lkml]   [2018]   [Jun]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH V5] powercap/drivers/idle_injection: Add an idle injection framework
    On Wed, Jun 06, 2018 at 03:42:08PM +0200, Daniel Lezcano wrote:
    > On 06/06/2018 14:23, Peter Zijlstra wrote:
    > > On Tue, Jun 05, 2018 at 11:16:40AM +0200, Daniel Lezcano wrote:
    > >> + atomic_t idle_duration_ms;
    > >> + atomic_t run_duration_ms;
    > >
    > >> + idle_duration_ms = atomic_read(&ii_dev->idle_duration_ms);
    > >
    > >> + run_duration_ms = atomic_read(&ii_dev->run_duration_ms);
    > >
    > >> + atomic_set(&ii_dev->run_duration_ms, run_duration_ms);
    > >> + atomic_set(&ii_dev->idle_duration_ms, idle_duration_ms);
    > >
    > >> + *run_duration_ms = atomic_read(&ii_dev->run_duration_ms);
    > >> + *idle_duration_ms = atomic_read(&ii_dev->idle_duration_ms);
    > >
    > >> + if (!atomic_read(&ii_dev->idle_duration_ms))
    > >
    > >> + if (!atomic_read(&ii_dev->run_duration_ms))
    > >
    > > What is the point of atomic_t here ?!
    >
    > idle_duration and run_duration can be changed from different places at
    > the same time. The atomic is here to ensure the read/write are consistent.
    >
    > Do you think it is pointless ?

    Yes, atomic_read() / atomic_set() are no more atomic than READ_ONCE() /
    WRITE_ONCE().

    \
     
     \ /
      Last update: 2018-06-06 17:02    [W:4.625 / U:0.164 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site