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

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Message-ID: <20241116192306.88217-3-sshegde@linux.ibm.com>
Date: Sun, 17 Nov 2024 00:53:06 +0530
From: Shrikanth Hegde <sshegde@...ux.ibm.com>
To: mpe@...erman.id.au, linuxppc-dev@...ts.ozlabs.org
Cc: sshegde@...ux.ibm.com, npiggin@...il.com, christophe.leroy@...roup.eu,
        maddy@...ux.ibm.com, bigeasy@...utronix.de, ankur.a.arora@...cle.com,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/2] powerpc: Large user copy aware of full:rt:lazy preemption

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@...utronix.de>
Signed-off-by: Shrikanth Hegde <sshegde@...ux.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