Re: [tip:sched/core] sched, tile: Remove finish_arch_switch

Re: [tip:sched/core] sched, tile: Remove finish_arch_switch

[Chris Metcalf]

Ingo,

I already have the appended commit in a modified form in the linux-tile
tree ready to be pushed to 4.3.  Can you drop it from your series?

Thanks!

On 8/4/2015 4:50 AM, tip-bot for Chris Metcalf wrote:
> Commit-ID:  fe363adb922583bacfbd5a30a4c773ccff9bb393
> Gitweb:     http://git.kernel.org/tip/fe363adb922583bacfbd5a30a4c773ccff9bb393
> Author:     Chris Metcalf <cmetcalf@ezchip.com>
> AuthorDate: Wed, 29 Jul 2015 13:06:29 -0400
> Committer:  Ingo Molnar <mingo@kernel.org>
> CommitDate: Tue, 4 Aug 2015 09:38:18 +0200
>
> sched, tile: Remove finish_arch_switch
>
> Move the simulator bits into switch_to() and use
> finish_arch_post_lock_switch() for the homecache migration bits.
>
> Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
> ---
>   arch/tile/include/asm/switch_to.h | 10 +++-------
>   arch/tile/kernel/process.c        | 17 +++++++++++++++--
>   2 files changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/arch/tile/include/asm/switch_to.h b/arch/tile/include/asm/switch_to.h
> index b8f888c..422842a 100644
> --- a/arch/tile/include/asm/switch_to.h
> +++ b/arch/tile/include/asm/switch_to.h
> @@ -53,15 +53,11 @@ extern unsigned long get_switch_to_pc(void);
>    * Kernel threads can check to see if they need to migrate their
>    * stack whenever they return from a context switch; for user
>    * threads, we defer until they are returning to user-space.
> + * We defer homecache migration until the runqueue lock is released.
>    */
> -#define finish_arch_switch(prev) do {                                     \
> -	if (unlikely((prev)->state == TASK_DEAD))                         \
> -		__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |       \
> -			((prev)->pid << _SIM_CONTROL_OPERATOR_BITS));     \
> -	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_SWITCH |             \
> -		(current->pid << _SIM_CONTROL_OPERATOR_BITS));            \
> +#define finish_arch_post_lock_switch() do {                               \
>   	if (current->mm == NULL && !kstack_hash &&                        \
> -	    current_thread_info()->homecache_cpu != smp_processor_id())   \
> +	    current_thread_info()->homecache_cpu != raw_smp_processor_id()) \
>   		homecache_migrate_kthread();                              \
>   } while (0)
>   
> diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c
> index a452137..1087375 100644
> --- a/arch/tile/kernel/process.c
> +++ b/arch/tile/kernel/process.c
> @@ -448,11 +448,24 @@ struct task_struct *__sched _switch_to(struct task_struct *prev,
>   
>   	/*
>   	 * Switch kernel SP, PC, and callee-saved registers.
> +	 * Pass the value to use for SYSTEM_SAVE_K_0 when we reset our sp.
> +	 * Once we return from this function we will have changed stacks
> +	 * and be running with current == next.
> +	 */
> +	__switch_to(prev, next, next_current_ksp0(next));
> +
> +	/* Notify the simulator of task switch and task exit. */
> +	if (unlikely(prev->state == TASK_DEAD))
> +		__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |
> +			     (prev->pid << _SIM_CONTROL_OPERATOR_BITS));
> +	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_SWITCH |
> +		(next->pid << _SIM_CONTROL_OPERATOR_BITS));
> +
> +	/*
>   	 * In the context of the new task, return the old task pointer
>   	 * (i.e. the task that actually called __switch_to).
> -	 * Pass the value to use for SYSTEM_SAVE_K_0 when we reset our sp.
>   	 */
> -	return __switch_to(prev, next, next_current_ksp0(next));
> +	return prev;
>   }
>   
>   /*

-- 
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com

Re: [tip:sched/core] sched, tile: Remove finish_arch_switch

[Ingo Molnar]

* Chris Metcalf <cmetcalf@ezchip.com> wrote:

> Ingo,
> 
> I already have the appended commit in a modified form in the linux-tile
> tree ready to be pushed to 4.3.  Can you drop it from your series?

Could you please post the updated patch? I cannot easily drop the patch because 
that would break the scheduler tree on the tile architecture.

Thanks,

	Ingo

[PATCH v2] tile: Remove finish_arch_switch

[Chris Metcalf]

Move the simulator bits into switch_to() and use
finish_arch_post_lock_switch() for the homecache migration bits.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
---
 arch/tile/include/asm/switch_to.h | 8 +++-----
 arch/tile/kernel/process.c        | 5 +++++
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/tile/include/asm/switch_to.h b/arch/tile/include/asm/switch_to.h
index b8f888cbe6b0..34ee72705521 100644
--- a/arch/tile/include/asm/switch_to.h
+++ b/arch/tile/include/asm/switch_to.h
@@ -53,15 +53,13 @@ extern unsigned long get_switch_to_pc(void);
  * Kernel threads can check to see if they need to migrate their
  * stack whenever they return from a context switch; for user
  * threads, we defer until they are returning to user-space.
+ * We defer homecache migration until the runqueue lock is released.
  */
-#define finish_arch_switch(prev) do {                                     \
-	if (unlikely((prev)->state == TASK_DEAD))                         \
-		__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |       \
-			((prev)->pid << _SIM_CONTROL_OPERATOR_BITS));     \
+#define finish_arch_post_lock_switch() do {                               \
 	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_SWITCH |             \
 		(current->pid << _SIM_CONTROL_OPERATOR_BITS));            \
 	if (current->mm == NULL && !kstack_hash &&                        \
-	    current_thread_info()->homecache_cpu != smp_processor_id())   \
+	    current_thread_info()->homecache_cpu != raw_smp_processor_id()) \
 		homecache_migrate_kthread();                              \
 } while (0)
 
diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c
index a45213781ad0..7d5769310bef 100644
--- a/arch/tile/kernel/process.c
+++ b/arch/tile/kernel/process.c
@@ -446,6 +446,11 @@ struct task_struct *__sched _switch_to(struct task_struct *prev,
 	hardwall_switch_tasks(prev, next);
 #endif
 
+	/* Notify the simulator of task exit. */
+	if (unlikely(prev->state == TASK_DEAD))
+		__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |
+			     (prev->pid << _SIM_CONTROL_OPERATOR_BITS));
+
 	/*
 	 * Switch kernel SP, PC, and callee-saved registers.
 	 * In the context of the new task, return the old task pointer
-- 
2.1.2

[tip:sched/core] tile: Reorganize _switch_to()

[tip-bot for Chris Metcalf]

Commit-ID:  1eaef888158dc441dcd00c20779251cfa5e756b3
Gitweb:     http://git.kernel.org/tip/1eaef888158dc441dcd00c20779251cfa5e756b3
Author:     Chris Metcalf <cmetcalf@ezchip.com>
AuthorDate: Wed, 5 Aug 2015 10:03:32 -0400
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Sat, 8 Aug 2015 10:29:21 +0200

tile: Reorganize _switch_to()

Move the simulator bits into finish_arch_post_lock_switch() and
properly call __switch_to() from _switch_to().

Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
Cc: <efault@gmx.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1438783412-10990-1-git-send-email-cmetcalf@ezchip.com
[ Made it a delta to: fe363adb9225 ("sched, tile: Remove finish_arch_switch"). ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/tile/include/asm/switch_to.h |  2 ++
 arch/tile/kernel/process.c        | 16 ++++------------
 2 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/arch/tile/include/asm/switch_to.h b/arch/tile/include/asm/switch_to.h
index 422842a..34ee727 100644
--- a/arch/tile/include/asm/switch_to.h
+++ b/arch/tile/include/asm/switch_to.h
@@ -56,6 +56,8 @@ extern unsigned long get_switch_to_pc(void);
  * We defer homecache migration until the runqueue lock is released.
  */
 #define finish_arch_post_lock_switch() do {                               \
+	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_SWITCH |             \
+		(current->pid << _SIM_CONTROL_OPERATOR_BITS));            \
 	if (current->mm == NULL && !kstack_hash &&                        \
 	    current_thread_info()->homecache_cpu != raw_smp_processor_id()) \
 		homecache_migrate_kthread();                              \
diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c
index 1087375..7d57693 100644
--- a/arch/tile/kernel/process.c
+++ b/arch/tile/kernel/process.c
@@ -446,26 +446,18 @@ struct task_struct *__sched _switch_to(struct task_struct *prev,
 	hardwall_switch_tasks(prev, next);
 #endif
 
-	/*
-	 * Switch kernel SP, PC, and callee-saved registers.
-	 * Pass the value to use for SYSTEM_SAVE_K_0 when we reset our sp.
-	 * Once we return from this function we will have changed stacks
-	 * and be running with current == next.
-	 */
-	__switch_to(prev, next, next_current_ksp0(next));
-
-	/* Notify the simulator of task switch and task exit. */
+	/* Notify the simulator of task exit. */
 	if (unlikely(prev->state == TASK_DEAD))
 		__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |
 			     (prev->pid << _SIM_CONTROL_OPERATOR_BITS));
-	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_SWITCH |
-		(next->pid << _SIM_CONTROL_OPERATOR_BITS));
 
 	/*
+	 * Switch kernel SP, PC, and callee-saved registers.
 	 * In the context of the new task, return the old task pointer
 	 * (i.e. the task that actually called __switch_to).
+	 * Pass the value to use for SYSTEM_SAVE_K_0 when we reset our sp.
 	 */
-	return prev;
+	return __switch_to(prev, next, next_current_ksp0(next));
 }
 
 /*