sched/deadline: Use C bitfields for the state flags

Ask the compiler to use a single bit for storing true / false values,
instead of wasting the size of a whole int value.
Tested with gcc 5.4.0 on x86_64, and the compiler produces the expected
Assembly (similar to the Assembly code generated when explicitly accessing
the bits with bitmasks, "&" and "|").

Signed-off-by: luca abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1504778971-13573-5-git-send-email-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 33a01f4..0f897df 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -474,10 +474,10 @@ struct sched_dl_entity {
         * conditions between the inactive timer handler and the wakeup
         * code.
         */
-       int                             dl_throttled;
-       int                             dl_boosted;
-       int                             dl_yielded;
-       int                             dl_non_contending;
+       int                             dl_throttled      : 1;
+       int                             dl_boosted        : 1;
+       int                             dl_yielded        : 1;
+       int                             dl_non_contending : 1;
 
        /*
         * Bandwidth enforcement timer. Each -deadline task has its