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[06/30] entry: handle lazy rescheduling at user-exit

Message ID 20240213055554.1802415-7-ankur.a.arora@oracle.com
State New
Headers
Series PREEMPT_AUTO: support lazy rescheduling |

Commit Message

Ankur Arora Feb. 13, 2024, 5:55 a.m. UTC 
  The scheduling policy for TIF_NEED_RESCHED_LAZY is to allow the
running task to voluntarily schedule out, running it to completion.

For archs with GENERIC_ENTRY, do this by adding a check in
exit_to_user_mode_loop().

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Originally-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/87jzshhexi.ffs@tglx/
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
---
 include/linux/entry-common.h | 2 +-
 kernel/entry/common.c        | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Comments

Thomas Gleixner Feb. 19, 2024, 3:29 p.m. UTC | #1 
On Mon, Feb 12 2024 at 21:55, Ankur Arora wrote:
> The scheduling policy for TIF_NEED_RESCHED_LAZY is to allow the
> running task to voluntarily schedule out, running it to completion.
>
> For archs with GENERIC_ENTRY, do this by adding a check in

Please write out architectures. This is not twatter.

> exit_to_user_mode_loop().

Thanks,

        tglx
Ankur Arora Feb. 20, 2024, 10:38 p.m. UTC | #2 
Thomas Gleixner <tglx@linutronix.de> writes:

> On Mon, Feb 12 2024 at 21:55, Ankur Arora wrote:
>> The scheduling policy for TIF_NEED_RESCHED_LAZY is to allow the
>> running task to voluntarily schedule out, running it to completion.
>>
>> For archs with GENERIC_ENTRY, do this by adding a check in
>
> Please write out architectures. This is not twatter.

Thankfully not! Will fix (this and elsewhere).

>> exit_to_user_mode_loop().
>
> Thanks,
>
>         tglx


--
ankur
diff mbox series

Patch

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index b0fb775a600d..f5bb19369973 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -65,7 +65,7 @@ 
 #define EXIT_TO_USER_MODE_WORK						\
 	(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE |		\
 	 _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL |	\
-	 ARCH_EXIT_TO_USER_MODE_WORK)
+	 _TIF_NEED_RESCHED_LAZY | ARCH_EXIT_TO_USER_MODE_WORK)
 
 /**
  * arch_enter_from_user_mode - Architecture specific sanity check for user mode regs
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 88cb3c88aaa5..5c5befb05410 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -92,7 +92,7 @@  __always_inline unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
 
 		local_irq_enable_exit_to_user(ti_work);
 
-		if (ti_work & _TIF_NEED_RESCHED)
+		if (ti_work & (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY))
 			schedule();
 
 		if (ti_work & _TIF_UPROBE)