On Wed, Aug 21, 2019 at 09:09:07PM +0200, Thomas Gleixner wrote: > Using struct task_cputime for the expiry cache is a pretty odd choice and > comes with magic defines to rename the fields for usage in the expiry > cache. > > struct task_cputime is basically a u64 array with 3 members, but it has > distinct members. > > The expiry cache content is different than the content of task_cputime > because > > expiry[PROF] = task_cputime.stime + task_cputime.utime > expiry[VIRT] = task_cputime.utime > expiry[SCHED] = task_cputime.sum_exec_runtime > > So there is no direct mapping between task_cputime and the expiry cache and > the #define based remapping is just a horrible hack. > > Having the expiry cache array based allows further simplification of the > expiry code. > > To avoid an all in one cleanup which is hard to review add a temporary > anonymous union into struct task_cputime which allows array based access to > it. That requires to reorder the members. Add a build time sanity check to > validate that the members are at the same place. > > The union and the build time checks will be removed after conversion. > > Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Reviewed-by: Frederic Weisbecker <frede...@kernel.org>
