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Ingo Molnar f96eca4320 sched/headers: Introduce kernel/sched/build_policy.c and build multiple .c files there

Similarly to kernel/sched/build_utility.c, collect all 'scheduling policy' related
source code files into kernel/sched/build_policy.c:

    kernel/sched/idle.c

    kernel/sched/rt.c

    kernel/sched/cpudeadline.c
    kernel/sched/pelt.c

    kernel/sched/cputime.c
    kernel/sched/deadline.c

With the exception of fair.c, which we continue to build as a separate file
for build efficiency and parallelism reasons.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>

2022-02-23 10:58:33 +01:00

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SPDX-License-Identifier: GPL-2.0

The compilers are complaining about unused variables inside an if(0) scope

block. This is daft, shut them up.

ccflags-y += $(call cc-disable-warning, unused-but-set-variable)

These files are disabled because they produce non-interesting flaky coverage

that is not a function of syscall inputs. E.g. involuntary context switches.

KCOV_INSTRUMENT := n

Disable KCSAN to avoid excessive noise and performance degradation. To avoid

false positives ensure barriers implied by sched functions are instrumented.

KCSAN_SANITIZE := n KCSAN_INSTRUMENT_BARRIERS := y

ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)

According to Alan Modra alan@linuxcare.com.au, the -fno-omit-frame-pointer is

needed for x86 only. Why this used to be enabled for all architectures is beyond

me. I suspect most platforms don't need this, but until we know that for sure

I turn this off for IA-64 only. Andreas Schwab says it's also needed on m68k

to get a correct value for the wait-channel (WCHAN in ps). --davidm

CFLAGS_core.o := $(PROFILING) -fno-omit-frame-pointer endif

Build efficiency:

These compilation units have roughly the same size and complexity - so their

build parallelizes well and finishes roughly at once:

obj-y += core.o obj-y += fair.o obj-y += build_policy.o obj-y += build_utility.o

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