sync deputy and remote before processing request

Stephan Schmid <stephan_2303-S0/[email protected]>
Newsgroups gmane.linux.cluster.openmosix.devel
Message-ID <[email protected]> 
Hello

I made a patch that makes deputy and remote sync if they issue both a request. The request of remote is processed first.
Before returning to usermode remote should process the request of deputy, which issues the request again.
This should happen in remote_pre_usermode, but I think the request hasnt yet arrived on remote when it is executed.
I there a technique to suspend the remote process until something comes through the connection ?
After all my tests I think this problem doesnt cause race conditions but sometimes it needs five minutes or so until
a deputy request is processed (when there are lots of requests).
Signal delivery kills the process.
loop.c which was sent over the mailing list some time ago worked fine.
A program which did permanently fopen(), fseek() and fclose() system calls needed usually a while to migrate back if the request
was issued from deputy.

Greetings
Stephan Schmid

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patch010801 (text/plain, 7.1 KB) 
diff -rud temp5/hpc/comm.c workom/hpc/comm.c
--- temp5/hpc/comm.c	2006-07-23 12:02:02.000000000 +0200
+++ workom/hpc/comm.c	2006-07-31 20:12:09.000000000 +0200
@@ -522,9 +522,65 @@
 }
 
 
-int comm_send_req(struct socket *link, int type)
+int comm_send_req_deputy(struct socket *link, int type)
 {
 	struct omp_req req;
+	struct omp_req rreq;
+	int err;
 	req.type = type;
-	return comm_send(link, &req, sizeof(req));
+start:
+	err = comm_send(link, &req, sizeof(req));
+	if (err <0) return err;
+	err = comm_recv(link, &rreq, sizeof(rreq));
+	if (err <0) return err;
+	if (rreq.type != (req.type | REPLY))
+	{
+		struct omp_req treq;
+		treq.type = rreq.type | REPLY;
+		err = comm_send(link, & treq, sizeof(treq));
+		if (err <0) return err;
+		__deputy_process_communication(current,rreq);
+		goto start;
+	}
+	return 0;
+}
+
+int comm_send_req_remote(struct socket *link, int type)
+{
+	struct omp_req req;
+	struct omp_req rreq;
+	int err;
+	req.type = type;
+
+	err = comm_send(link, &req, sizeof(req));
+	if (err <0) return err;
+	err = comm_recv(link, &rreq, sizeof(rreq));
+	if (err <0) return err;
+	if (rreq.type != (req.type | REPLY))
+	{
+		task_set_dflags(current, DDREQPENDING);
+		OMDEBUG(4,"registered deputy req");
+		err = comm_recv(link, &rreq, sizeof(rreq));
+		if (rreq.type != (req.type | REPLY)) return -1;
+	}
+	return 0;
+}
+
+int comm_recv_req(struct socket *link, struct omp_req * dest)
+{
+	struct omp_req rreq;
+	int err;
+	err= comm_recv(link, dest, sizeof(rreq));
+	if (err <0) return err;
+	rreq.type = dest->type | REPLY;
+	err= comm_send(link, &rreq, sizeof(rreq));
+	if (err <0) return err;
+	return 0;
 }
+
+int comm_send_req(struct socket *link, int type) //this is without sync
+{
+	struct omp_req req;
+	req.type = type;
+	return comm_send(link, &req, sizeof(req));
+}
\ Kein Zeilenumbruch am Dateiende.
Nur in workom/hpc: comm.c~.
diff -rud temp5/hpc/deputy.c workom/hpc/deputy.c
--- temp5/hpc/deputy.c	2006-07-23 12:02:02.000000000 +0200
+++ workom/hpc/deputy.c	2006-07-30 14:25:34.000000000 +0200
@@ -45,8 +45,16 @@
 {
 	struct omp_syscall_req s;
 	struct omp_syscall_ret r;
+	struct omp_req req;
 	int error;
 	
+	error = comm_recv(p->om.contact, &req,sizeof(req));
+	if (error <0) return -1;
+	if (req.dlen != sizeof(s))
+	{
+		OMBUG("received %d instead of %d (sizeof(omp_syscall_req)), aborting syscall processing", req.dlen, sizeof(s));
+		return -1;
+	}
 	error = comm_recv(p->om.contact, &s, sizeof(s));
 	if (error < 0)
 		return -1;
@@ -416,15 +424,9 @@
 /**
  * deputy_process_communication - process has receive communication in deputy
  **/
-static void deputy_process_communication(task_t *p)
+void __deputy_process_communication(task_t *p, struct omp_req req)
 {
-	struct omp_req req;
 	int error;
-	
-	error = comm_recv(p->om.contact, &req, sizeof(req));
-	if (error < 0)
-		deputy_die_on_communication();
-
 	switch (req.type)
 	{
 	case 0:
@@ -456,6 +458,18 @@
 		deputy_die_on_communication();
 }
 
+static void deputy_process_communication(task_t *p)
+{
+	struct omp_req req;
+	int error;
+	
+	error = comm_recv_req(p->om.contact, &req);
+	if (error < 0)
+		deputy_die_on_communication();
+
+	__deputy_process_communication(p,req);
+}
+
 /**
  * deputy_main_loop - process loop when process is deputy
  **/
Nur in workom/hpc: deputy.c~.
diff -rud temp5/hpc/kernel.c workom/hpc/kernel.c
--- temp5/hpc/kernel.c	2006-07-23 12:02:02.000000000 +0200
+++ workom/hpc/kernel.c	2006-07-31 18:25:59.000000000 +0200
@@ -159,6 +159,11 @@
 {
 	task_t *p = current;
 
+	if(task_test_dflags(p,DDREQPENDING))
+	{
+		task_clear_dflags(p,DDREQPENDING);
+		remote_do_comm(p);
+	}
 	if (p->om.contact && comm_peek(p->om.contact))
 		remote_do_comm(p);
 	return 0;
Nur in workom/hpc: kernel.c~.
diff -rud temp5/hpc/migctrl.c workom/hpc/migctrl.c
--- temp5/hpc/migctrl.c	2006-07-23 12:02:02.000000000 +0200
+++ workom/hpc/migctrl.c	2006-07-29 12:12:58.000000000 +0200
@@ -66,9 +66,9 @@
 	int error;
 	struct omp_req req;
 
-	comm_send_req(p->om.contact, REM_BRING_HOME);
+	comm_send_req_remote(p->om.contact, REM_BRING_HOME);
 
-	error = comm_recv(p->om.contact, &req, sizeof(req));
+	error = comm_recv_req(p->om.contact, &req);
 	if (error < 0)
 		return -1;
 	if (req.type != DEP_COMING_HOME) {
@@ -144,7 +144,7 @@
 	}
 
 	/* send remote request */
-	comm_send_req(p->om.contact, DEP_COMING_HOME);
+	comm_send_req_deputy(p->om.contact, DEP_COMING_HOME);
 
 	/* see if other part is with on this */
 	if (mig_recv_hshake(p->om.contact))
Nur in workom/hpc: migctrl.c~.
diff -rud temp5/hpc/remote.c workom/hpc/remote.c
--- temp5/hpc/remote.c	2006-07-23 12:02:02.000000000 +0200
+++ workom/hpc/remote.c	2006-07-31 16:36:15.000000000 +0200
@@ -173,7 +173,7 @@
 	int error;
 	struct omp_req req;
 
-	error = comm_recv(p->om.contact, &req, sizeof(req));
+	error = comm_recv_req(p->om.contact, &req);
 	if (error < 0)
 		goto fail;
 
@@ -214,7 +214,11 @@
 	s.n = n;
 	for (i = 0; i < NR_MAX_SYSCALL_ARG; i++)
 		s.arg[i] = arch_get_sys_arg(i, regs);
+	error = comm_send_req_remote(p->om.contact, REM_SYSCALL);	
+	if (error < 0)
+		goto error;
 
+	OMDEBUG_SYS(3, "[remote] sysc. adv. sent, sending sysc_req");
 	error = comm_send_hd(p->om.contact, REM_SYSCALL, &s, sizeof(s));
 	if (error < 0)
 		goto error;
Nur in workom/hpc: remote.c~.
diff -rud temp5/include/hpc/comm.h workom/include/hpc/comm.h
--- temp5/include/hpc/comm.h	2006-07-23 12:02:02.000000000 +0200
+++ workom/include/hpc/comm.h	2006-07-29 12:47:26.000000000 +0200
@@ -61,7 +61,10 @@
 struct socket * comm_setup_listen(struct sockaddr *);
 struct socket * comm_setup_connect(struct sockaddr *, int);
 int comm_send_hd(struct socket *, int, void *, int);
-int comm_send_req(struct socket *link, int type);
+int comm_send_req_deputy(struct socket *link, int type);	//processes pending request from remote before
+int comm_send_req_remote(struct socket *link, int type);
+int comm_send_req(struct socket *link, int type);//without sync
+int comm_recv_req(struct socket *link, struct omp_req * dest);
 
 /* FIXME: oM task routines, this really should be in task.h,
  * but it causes problems there */
Nur in workom/include/hpc: comm.h~.
diff -rud temp5/include/hpc/prototype.h workom/include/hpc/prototype.h
--- temp5/include/hpc/prototype.h	2006-07-23 12:02:02.000000000 +0200
+++ workom/include/hpc/prototype.h	2006-07-29 12:46:51.000000000 +0200
@@ -32,6 +32,7 @@
 NORET_TYPE void		deputy_die_on_communication(void);
 void			deputy_main_loop(void);
 void			deputy_startup(task_t *p);
+void 			__deputy_process_communication(task_t *p, struct omp_req req); //used in comm.c (comm_send_req_deputy)
 
 /*****************************************************************************/
 
Nur in workom/include/hpc: prototype.h~.
diff -rud temp5/include/hpc/task.h workom/include/hpc/task.h
--- temp5/include/hpc/task.h	2006-07-23 12:02:02.000000000 +0200
+++ workom/include/hpc/task.h	2006-07-31 18:15:20.000000000 +0200
@@ -49,6 +49,10 @@
 
 #define	DMIGRATED	(DDEPUTY | DREMOTE) /* if task has been migrated */
 
+#define DDREQPENDING	0x00000800	/*deputy request pending set if\
+					comm_send_req_remote discovers a req.\
+					It is cleared by remote_pre_usermode*/
+
 /*
  * distributed request (dreqs):
  * Thoses flags are set by any process to interact with the process.
Nur in workom/include/hpc: task.h~.
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