[Xenomai-core] [RFC][PATCH 2/2] global CPU affinity control

[Jan Kiszka <jan.kiszka@domain.hid>]

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This is version 4 of the /proc/xenomai/affinity feature. It has been
rebased on the reworked xnshadow_map code, now applying the default
affinity mask in a (hopefully) correct way also on shadow threads.

What has been said for the previous patch also applies here: test and
comment! Mathias, you asked for this feature, please let us know if it
fulfils your requirements.

Philippe, you were looking for documentation of this new behaviour.
Please let me know where you would like to see this. Surely in the
nucleus API, I guess. Anywhere else?

Jan

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---
 include/nucleus/pod.h    |    2 +
 ksrc/nucleus/intr.c      |    3 ++
 ksrc/nucleus/module.c    |   57 +++++++++++++++++++++++++++++++++++++++++++++++
 ksrc/nucleus/pod.c       |    6 +++-
 ksrc/nucleus/shadow.c    |    3 ++
 ksrc/skins/native/task.c |    3 ++
 6 files changed, 72 insertions(+), 2 deletions(-)

Index: xenomai/include/nucleus/pod.h
===================================================================
--- xenomai.orig/include/nucleus/pod.h
+++ xenomai/include/nucleus/pod.h
@@ -256,6 +256,8 @@ extern u_long nktickdef;
 
 extern char *nkmsgbuf;
 
+extern xnarch_cpumask_t nkaffinity;
+
 #define xnprintf(fmt,args...)  xnarch_printf(fmt , ##args)
 #define xnloginfo(fmt,args...) xnarch_loginfo(fmt , ##args)
 #define xnlogwarn(fmt,args...) xnarch_logwarn(fmt , ##args)
Index: xenomai/ksrc/nucleus/module.c
===================================================================
--- xenomai.orig/ksrc/nucleus/module.c
+++ xenomai/ksrc/nucleus/module.c
@@ -688,6 +688,59 @@ static int heap_read_proc(char *page,
 	return len;
 }
 
+static int affinity_read_proc(char *page,
+			      char **start,
+			      off_t off, int count, int *eof, void *data)
+{
+	unsigned long val = 0;
+	int len, cpu;
+
+	for (cpu = 0; cpu < sizeof(val) * 8; cpu++)
+		if (xnarch_cpu_isset(cpu, nkaffinity))
+			val |= (1 << cpu);
+
+	len = sprintf(page, "%08lx\n", val);
+	len -= off;
+	if (len <= off + count)
+		*eof = 1;
+	*start = page + off;
+	if (len > count)
+		len = count;
+	if (len < 0)
+		len = 0;
+
+	return len;
+}
+
+static int affinity_write_proc(struct file *file,
+			       const char __user * buffer,
+			       unsigned long count, void *data)
+{
+	char *end, buf[16];
+	unsigned long val;
+	xnarch_cpumask_t new_affinity;
+	int n, cpu;
+
+	n = count > sizeof(buf) - 1 ? sizeof(buf) - 1 : count;
+
+	if (copy_from_user(buf, buffer, n))
+		return -EFAULT;
+
+	buf[n] = '\0';
+	val = simple_strtol(buf, &end, 0);
+
+	if (*end != '\0' && !isspace(*end))
+		return -EINVAL;
+
+	xnarch_cpus_clear(new_affinity);
+	for (cpu = 0; cpu < sizeof(val) * 8; cpu++, val >>= 1)
+		if (val & 1)
+			xnarch_cpu_set(cpu, new_affinity);
+	nkaffinity = new_affinity;
+
+	return count;
+}
+
 static struct proc_dir_entry *add_proc_leaf(const char *name,
 					    read_proc_t rdproc,
 					    write_proc_t wrproc,
@@ -760,6 +813,9 @@ void xnpod_init_proc(void)
 
 	add_proc_leaf("heap", &heap_read_proc, NULL, NULL, rthal_proc_root);
 
+	add_proc_leaf("affinity", &affinity_read_proc, &affinity_write_proc,
+		      NULL, rthal_proc_root);
+
 #ifdef CONFIG_XENO_OPT_PERVASIVE
 	iface_proc_root =
 	    create_proc_entry("interfaces", S_IFDIR, rthal_proc_root);
@@ -778,6 +834,7 @@ void xnpod_delete_proc(void)
 
 	remove_proc_entry("interfaces", rthal_proc_root);
 #endif /* CONFIG_XENO_OPT_PERVASIVE */
+	remove_proc_entry("affinity", rthal_proc_root);
 	remove_proc_entry("heap", rthal_proc_root);
 	remove_proc_entry("irq", rthal_proc_root);
 	remove_proc_entry("timer", rthal_proc_root);
Index: xenomai/ksrc/nucleus/pod.c
===================================================================
--- xenomai.orig/ksrc/nucleus/pod.c
+++ xenomai/ksrc/nucleus/pod.c
@@ -70,6 +70,8 @@ MODULE_PARM_DESC(tick_arg, "Fixed clock 
 
 char *nkmsgbuf = NULL;
 
+xnarch_cpumask_t nkaffinity = XNPOD_ALL_CPUS;
+
 const char *xnpod_fatal_helper(const char *format, ...)
 {
 	const unsigned nr_cpus = xnarch_num_online_cpus();
@@ -909,8 +911,8 @@ int xnpod_start_thread(xnthread_t *threa
 	if (!testbits(thread->status, XNDORMANT))
 		return -EBUSY;
 
-	if (xnarch_cpus_empty(affinity))
-		affinity = XNARCH_CPU_MASK_ALL;
+	if (xnarch_cpus_equal(affinity, XNPOD_ALL_CPUS))
+		affinity = nkaffinity;
 
 	xnlock_get_irqsave(&nklock, s);
 
Index: xenomai/ksrc/nucleus/shadow.c
===================================================================
--- xenomai.orig/ksrc/nucleus/shadow.c
+++ xenomai/ksrc/nucleus/shadow.c
@@ -847,6 +847,9 @@ int xnshadow_map(xnthread_t *thread, xnc
 	xnshadow_thrptd(current) = thread;
 	xnpod_suspend_thread(thread, XNRELAX, XN_INFINITE, NULL);
 
+	if (xnarch_cpus_equal(affinity, XNPOD_ALL_CPUS))
+		affinity = nkaffinity;
+
 	/* Apply provided cpumask on the Linux task. */
 	set_cpus_allowed(current, affinity);
 
Index: xenomai/ksrc/skins/native/task.c
===================================================================
--- xenomai.orig/ksrc/skins/native/task.c
+++ xenomai/ksrc/skins/native/task.c
@@ -255,6 +255,9 @@ int rt_task_create(RT_TASK *task,
 		if (cpumask & 1)
 			xnarch_cpu_set(cpu, task->affinity);
 
+	if (xnarch_cpus_empty(task->affinity))
+		task->affinity = XNPOD_ALL_CPUS;
+
 #ifdef CONFIG_XENO_OPT_NATIVE_MPS
 	xnsynch_init(&task->mrecv, XNSYNCH_FIFO);
 	xnsynch_init(&task->msendq, XNSYNCH_PRIO | XNSYNCH_PIP);
Index: xenomai/ksrc/nucleus/intr.c
===================================================================
--- xenomai.orig/ksrc/nucleus/intr.c
+++ xenomai/ksrc/nucleus/intr.c
@@ -626,6 +626,9 @@ int xnintr_attach(xnintr_t *intr, void *
 
 	xnlock_get_irqsave(&intrlock, s);
 
+#ifdef CONFIG_SMP
+	xnarch_set_irq_affinity(intr->irq, nkaffinity);
+#endif /* CONFIG_SMP */
 	err = xnintr_irq_attach(intr);
 
 	xnlock_put_irqrestore(&intrlock, s);

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