kernel: optimize the no signal chksigs() case

diff --git a/Kernel/include/kernel.h b/Kernel/include/kernel.h
index 1bbae6e..dc4cb84 100644 (file)
--- 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 d5ccc45..09044ed 100644 (file)
--- 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 */