Give make(1) the ability to use KQUEUE to wait for worker processes

instead of polling for them.

Unfortunately we cannot enable it yet because it panics the kernel
somewhere in kqueue.

Submitted by:	Stefan Farfeleder <e0026813@stud3.tuwien.ac.at>

3 files changed, 57 insertions, 1 deletions

diff --git a/usr.bin/make/Makefile b/usr.bin/make/Makefile
index 88027b21..af802d0 100644
--- a/usr.bin/make/Makefile
+++ b/usr.bin/make/Makefile
@@ -20,6 +20,9 @@ CFLAGS+=-DMAKE_VERSION=\"5200209170\"
 CFLAGS+=-D__FBSDID=__RCSID
 .endif
 
+# XXX: kernel currently broken
+# CFLAGS+=-DUSE_KQUEUE
+
 main.o: ${MAKEFILE}
 
 # Set the shell which make(1) uses.  Bourne is the default, but a decent
diff --git a/usr.bin/make/job.c b/usr.bin/make/job.c
index 92264b2..7026b88 100644
--- a/usr.bin/make/job.c
+++ b/usr.bin/make/job.c
@@ -106,6 +106,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/stat.h>
 #include <sys/file.h>
 #include <sys/time.h>
+#include <sys/event.h>
 #include <sys/wait.h>
 #include <err.h>
 #include <errno.h>
@@ -237,9 +238,13 @@ STATIC Boolean	jobFull;    	/* Flag to tell when the job table is full. It
 				 * (2) a job can only be run locally, but
 				 * nLocal equals maxLocal */
 #ifndef RMT_WILL_WATCH
+#ifdef USE_KQUEUE
+static int	kqfd;		/* File descriptor obtained by kqueue() */
+#else
 static fd_set  	outputs;    	/* Set of descriptors of pipes connected to
 				 * the output channels of children */
 #endif
+#endif
 
 STATIC GNode   	*lastNode;	/* The node for which output was most recently
 				 * produced. */
@@ -692,7 +697,7 @@ JobClose(job)
     if (usePipes) {
 #ifdef RMT_WILL_WATCH
 	Rmt_Ignore(job->inPipe);
-#else
+#elif !defined(USE_KQUEUE)
 	FD_CLR(job->inPipe, &outputs);
 #endif
 	if (job->outPipe != job->inPipe) {
@@ -1267,10 +1272,22 @@ JobExec(job, argv)
 	     * position in the buffer to the beginning and mark another
 	     * stream to watch in the outputs mask
 	     */
+#ifdef USE_KQUEUE
+	    struct kevent	kev[2];
+#endif
 	    job->curPos = 0;
 
 #ifdef RMT_WILL_WATCH
 	    Rmt_Watch(job->inPipe, JobLocalInput, job);
+#elif defined(USE_KQUEUE)
+	    EV_SET(&kev[0], job->inPipe, EVFILT_READ, EV_ADD, 0, 0, job);
+	    EV_SET(&kev[1], job->pid, EVFILT_PROC, EV_ADD | EV_ONESHOT,
+		NOTE_EXIT, 0, NULL);
+	    if (kevent(kqfd, kev, 2, NULL, 0, NULL) != 0) {
+		/* kevent() will fail if the job is already finished */
+		if (errno != EBADF && errno != ESRCH)
+		    Punt("kevent: %s", strerror(errno));
+	    }
 #else
 	    FD_SET(job->inPipe, &outputs);
 #endif /* RMT_WILL_WATCH */
@@ -2229,10 +2246,16 @@ void
 Job_CatchOutput()
 {
     int           	  nfds;
+#ifdef USE_KQUEUE
+#define KEV_SIZE	4
+    struct kevent	  kev[KEV_SIZE];
+    int			  i;
+#else
     struct timeval	  timeout;
     fd_set           	  readfds;
     LstNode		  ln;
     Job		   	  *job;
+#endif
 #ifdef RMT_WILL_WATCH
     int	    	  	  pnJobs;   	/* Previous nJobs */
 #endif
@@ -2262,6 +2285,27 @@ Job_CatchOutput()
     }
 #else
     if (usePipes) {
+#ifdef USE_KQUEUE
+	if ((nfds = kevent(kqfd, NULL, 0, kev, KEV_SIZE, NULL)) == -1) {
+	    Punt("kevent: %s", strerror(errno));
+	} else {
+	    for (i = 0; i < nfds; i++) {
+		if (kev[i].flags & EV_ERROR) {
+		    warnc(kev[i].data, "kevent");
+		    continue;
+		}
+		switch (kev[i].filter) {
+		case EVFILT_READ:
+		    JobDoOutput(kev[i].udata, FALSE);
+		    break;
+		case EVFILT_PROC:
+		    /* Just wake up and let Job_CatchChildren() collect the
+		     * terminated job. */
+		    break;
+		}
+	    }
+	}
+#else
 	readfds = outputs;
 	timeout.tv_sec = SEL_SEC;
 	timeout.tv_usec = SEL_USEC;
@@ -2282,6 +2326,7 @@ Job_CatchOutput()
 	    }
 	    Lst_Close(jobs);
 	}
+#endif /* !USE_KQUEUE */
     }
 #endif /* RMT_WILL_WATCH */
 }
@@ -2411,6 +2456,12 @@ Job_Init(maxproc, maxlocal)
     }
 #endif
 
+#ifdef USE_KQUEUE
+    if ((kqfd = kqueue()) == -1) {
+	Punt("kqueue: %s", strerror(errno));
+    }
+#endif
+
     begin = Targ_FindNode(".BEGIN", TARG_NOCREATE);
 
     if (begin != NULL) {
diff --git a/usr.bin/make/job.h b/usr.bin/make/job.h
index f5d406b..6220e09 100644
--- a/usr.bin/make/job.h
+++ b/usr.bin/make/job.h
@@ -50,6 +50,7 @@
 
 #define	TMPPAT	"/tmp/makeXXXXXXXXXX"
 
+#ifndef USE_KQUEUE
 /*
  * The SEL_ constants determine the maximum amount of time spent in select
  * before coming out to see if a child has finished. SEL_SEC is the number of
@@ -57,6 +58,7 @@
  */
 #define	SEL_SEC		0
 #define	SEL_USEC	100000
+#endif /* !USE_KQUEUE */
 
 
 /*-