From: Russell King <rmk@dyn-67.arm.linux.org.uk>
Date: Sun, 27 Aug 2006 11:38:34 +0000 (+0100)
Subject: [ARM] Optimise VFP thread notify function a little
X-Git-Tag: v2.6.19-rc1~885^2~77
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=681a4991f83742a0d2325afbf7b7f22045ad5b30;p=linux-2.6

[ARM] Optimise VFP thread notify function a little

The common case for the thread notifier is a context switch.  Tell
gcc that this is the most likely condition so it can optimise the
function for this case.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 4178f6cc3d..dedbb44963 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -40,10 +40,19 @@ unsigned int VFP_arch;
 static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
 {
 	struct thread_info *thread = v;
-	union vfp_state *vfp = &thread->vfpstate;
+	union vfp_state *vfp;
 
-	switch (cmd) {
-	case THREAD_NOTIFY_FLUSH:
+	if (likely(cmd == THREAD_NOTIFY_SWITCH)) {
+		/*
+		 * Always disable VFP so we can lazily save/restore the
+		 * old state.
+		 */
+		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
+		return NOTIFY_DONE;
+	}
+
+	vfp = &thread->vfpstate;
+	if (cmd == THREAD_NOTIFY_FLUSH) {
 		/*
 		 * Per-thread VFP initialisation.
 		 */
@@ -56,29 +65,12 @@ static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
 		 * Disable VFP to ensure we initialise it first.
 		 */
 		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
-
-		/*
-		 * FALLTHROUGH: Ensure we don't try to overwrite our newly
-		 * initialised state information on the first fault.
-		 */
-
-	case THREAD_NOTIFY_RELEASE:
-		/*
-		 * Per-thread VFP cleanup.
-		 */
-		if (last_VFP_context == vfp)
-			last_VFP_context = NULL;
-		break;
-
-	case THREAD_NOTIFY_SWITCH:
-		/*
-		 * Always disable VFP so we can lazily save/restore the
-		 * old state.
-		 */
-		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
-		break;
 	}
 
+	/* flush and release case: Per-thread VFP cleanup. */
+	if (last_VFP_context == vfp)
+		last_VFP_context = NULL;
+
 	return NOTIFY_DONE;
 }