Messages in this thread | | | Subject | Re: [PATCH RFC] sched: Micro optimization in pick_next_task() and in check_preempt_curr() | From | Kirill Tkhai <> | Date | Thu, 19 Dec 2019 16:53:33 +0300 |
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On 19.12.2019 16:50, Steven Rostedt wrote: > On Thu, 19 Dec 2019 15:39:14 +0300 > Kirill Tkhai <ktkhai@virtuozzo.com> wrote: > >> @@ -6569,6 +6558,11 @@ void __init sched_init(void) >> unsigned long ptr = 0; >> int i; >> >> + BUG_ON(&idle_sched_class > &fair_sched_class || >> + &fair_sched_class > &rt_sched_class || >> + &rt_sched_class > &dl_sched_class || >> + &dl_sched_class > &stop_sched_class); >> + > > Can this be a BUILD_BUG_ON? These address should all be constants.
BUILD_BUG_ON() is compile-time check, while address is assigned at link time, isn't it?!
Anyway, plain BUILD_BUG_ON() fails here with the following:
In file included from ./arch/x86/include/asm/current.h:5, from ./include/linux/sched.h:12, from kernel/sched/sched.h:5, from kernel/sched/core.c:9: kernel/sched/core.c: In function ‘sched_init’: ./include/linux/compiler.h:394:38: error: call to ‘__compiletime_assert_6561’ declared with attribute error: BUILD_BUG_ON failed: &idle_sched_class > &fair_sched_class || &fair_sched_class > &rt_sched_class || &rt_sched_class > &dl_sched_class || &dl_sched_class > &stop_sched_class 394 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) | ^ ./include/linux/compiler.h:375:4: note: in definition of macro ‘__compiletime_assert’ 375 | prefix ## suffix(); \ | ^~~~~~ ./include/linux/compiler.h:394:2: note: in expansion of macro ‘_compiletime_assert’ 394 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) | ^~~~~~~~~~~~~~~~~~~ ./include/linux/build_bug.h:39:37: note: in expansion of macro ‘compiletime_assert’ 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) | ^~~~~~~~~~~~~~~~~~ ./include/linux/build_bug.h:50:2: note: in expansion of macro ‘BUILD_BUG_ON_MSG’ 50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) | ^~~~~~~~~~~~~~~~ kernel/sched/core.c:6561:2: note: in expansion of macro ‘BUILD_BUG_ON’ 6561 | BUILD_BUG_ON(&idle_sched_class > &fair_sched_class || | ^~~~~~~~~~~~
> -- Steve > > > >> wait_bit_init(); >>
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