[PATCH v2 2/2] powerpc: Large user copy aware of full:rt:lazy preemption

Shrikanth Hegde sshegde at linux.ibm.com
Sun Nov 17 06:23:06 AEDT 2024


Large user copy_to/from (more than 16 bytes) uses vmx instructions to 
speed things up. Once the copy is done, it makes sense to try schedule 
as soon as possible for preemptible kernels. So do this for 
preempt=full/lazy and rt kernel. 

Not checking for lazy bit here, since it could lead to unnecessary 
context switches.

Suggested-by: Sebastian Andrzej Siewior <bigeasy at linutronix.de>
Signed-off-by: Shrikanth Hegde <sshegde at linux.ibm.com>
---
 arch/powerpc/lib/vmx-helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/lib/vmx-helper.c b/arch/powerpc/lib/vmx-helper.c
index d491da8d1838..58ed6bd613a6 100644
--- a/arch/powerpc/lib/vmx-helper.c
+++ b/arch/powerpc/lib/vmx-helper.c
@@ -45,7 +45,7 @@ int exit_vmx_usercopy(void)
 	 * set and we are preemptible. The hack here is to schedule a
 	 * decrementer to fire here and reschedule for us if necessary.
 	 */
-	if (IS_ENABLED(CONFIG_PREEMPT) && need_resched())
+	if (IS_ENABLED(CONFIG_PREEMPTION) && need_resched())
 		set_dec(1);
 	return 0;
 }
-- 
2.43.5



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