From: Alan Cox <alan@linux.intel.com>
Date: Fri, 16 Nov 2018 19:38:27 +0000 (+0000)
Subject: kernel: optimize the no signal chksigs() case
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=70fe421e03abda1bb8aa0f159d1f2cad66ece3e4;p=FUZIX.git

kernel: optimize the no signal chksigs() case
---

diff --git a/Kernel/include/kernel.h b/Kernel/include/kernel.h
index 1bbae6e1..dc4cb840 100644
--- a/Kernel/include/kernel.h
+++ b/Kernel/include/kernel.h
@@ -480,8 +480,6 @@ typedef struct p_tab {
 #ifdef udata
     struct u_data *p_udata;	/* Udata pointer for platforms using dynamic udata */
 #endif
-    /* Everything below here is overlaid by time info at exit.
-	 * Make sure it's 32-bit aligned. */
     uint16_t    p_priority;     /* Process priority */
     struct sigbits p_sig[2];
     uint16_t    p_waitno;       /* wait #; for finding longest waiting proc */
@@ -496,6 +494,8 @@ typedef struct p_tab {
     uint8_t	p_nice;
     uint8_t	p_event;	/* Events */
     usize_t	p_top;		/* Copy of u_top */
+    uint8_t	p_flags;	/* Bitflags */
+#define PFL_CHKSIG	1	/* Signal check required */
 #ifdef CONFIG_PROFIL
     uint8_t	p_profscale;
     void *	p_profbuf;
diff --git a/Kernel/process.c b/Kernel/process.c
index d5ccc45c..09044ed8 100644
--- a/Kernel/process.c
+++ b/Kernel/process.c
@@ -569,6 +569,10 @@ void recalc_cursig(void)
 		sb->s_pending |= 1 << udata.u_cursig;
 		udata.u_cursig = 0;
 	}
+	/* This function gets called on things like signal mask changes
+	   so even if no signal was pending there might be one next time
+	   we ask */
+	udata.u_ptab->p_flags |= PFL_CHKSIG;
 }
 
 /* Process a block of 16 signals so we can avoid using longs */
@@ -670,7 +674,7 @@ uint8_t chksigs(void)
 	   Cursig being set means we've already worked out what to do.
 	 */
 rescan:
-	if (udata.u_cursig || udata.u_ptab->p_status == P_STOPPED)
+	if (udata.u_cursig || !(udata.u_ptab->p_flags & PFL_CHKSIG) || udata.u_ptab->p_status == P_STOPPED)
 		return udata.u_cursig;
 
 	for (b = 0; b < 2; b++, sb++) {
@@ -680,6 +684,8 @@ rescan:
 		else if (r)
 			return udata.u_cursig;
 	}
+	/* No signal pending, remember this */
+	udata.u_ptab->p_flags &= ~PFL_CHKSIG;
 	return 0;
 }
 
@@ -706,6 +712,7 @@ void ssig(ptptr proc, uint8_t sig)
 	irq = di();
 
 	if (proc->p_status != P_EMPTY) {	/* Presumably was killed just now */
+		proc->p_flags |= PFL_CHKSIG;
                 /* SIGCONT has an unblockable effect */
 		if (sig == SIGCONT) {
 			/* You can never send yourself a SIGCONT when you are stopped */