SMP IRQ affinity
-/proc/irq/IRQ#/smp_affinity specifies which target CPUs are permitted
-for a given IRQ source. It's a bitmask of allowed CPUs. It's not allowed
-to turn off all CPUs, and if an IRQ controller does not support IRQ
-affinity then the value will not change from the default 0xffffffff.
+/proc/irq/IRQ#/smp_affinity and /proc/irq/IRQ#/smp_affinity_list specify
+which target CPUs are permitted for a given IRQ source. It's a bitmask
+(smp_affinity) or cpu list (smp_affinity_list) of allowed CPUs. It's not
+allowed to turn off all CPUs, and if an IRQ controller does not support
+IRQ affinity then the value will not change from the default of all cpus.
/proc/irq/default_smp_affinity specifies default affinity mask that applies
to all non-active IRQs. Once IRQ is allocated/activated its affinity bitmask
This time around IRQ44 was delivered only to the last four processors.
i.e counters for the CPU0-3 did not change.
+Here is an example of limiting that same irq (44) to cpus 1024 to 1031:
+
+[root@moon 44]# echo 1024-1031 > smp_affinity
+[root@moon 44]# cat smp_affinity
+1024-1031
+
+Note that to do this with a bitmask would require 32 bitmasks of zero
+to follow the pertinent one.
> cat /proc/irq/0/smp_affinity
ffffffff
+There is an alternate interface, smp_affinity_list which allows specifying
+a cpu range instead of a bitmask:
+
+ > cat /proc/irq/0/smp_affinity_list
+ 1024-1031
+
The default_smp_affinity mask applies to all non-active IRQs, which are the
IRQs which have not yet been allocated/activated, and hence which lack a
/proc/irq/[0-9]* directory.
include information about any possible driver locality preference.
prof_cpu_mask specifies which CPUs are to be profiled by the system wide
-profiler. Default value is ffffffff (all cpus).
+profiler. Default value is ffffffff (all cpus if there are only 32 of them).
The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
between all the CPUs which are allowed to handle it. As usual the kernel has
more info than you and does a better job than you, so the defaults are the
-best choice for almost everyone.
+best choice for almost everyone. [Note this applies only to those IO-APIC's
+that support "Round Robin" interrupt distribution.]
There are three more important subdirectories in /proc: net, scsi, and sys.
The general rule is that the contents, or even the existence of these
* bitmap_parse(buf, buflen, dst, nbits) Parse bitmap dst from kernel buf
* bitmap_parse_user(ubuf, ulen, dst, nbits) Parse bitmap dst from user buf
* bitmap_scnlistprintf(buf, len, src, nbits) Print bitmap src as list to buf
- * bitmap_parselist(buf, dst, nbits) Parse bitmap dst from list
+ * bitmap_parselist(buf, dst, nbits) Parse bitmap dst from kernel buf
+ * bitmap_parselist_user(buf, dst, nbits) Parse bitmap dst from user buf
* bitmap_find_free_region(bitmap, bits, order) Find and allocate bit region
* bitmap_release_region(bitmap, pos, order) Free specified bit region
* bitmap_allocate_region(bitmap, pos, order) Allocate specified bit region
const unsigned long *src, int nbits);
extern int bitmap_parselist(const char *buf, unsigned long *maskp,
int nmaskbits);
+extern int bitmap_parselist_user(const char __user *ubuf, unsigned int ulen,
+ unsigned long *dst, int nbits);
extern void bitmap_remap(unsigned long *dst, const unsigned long *src,
const unsigned long *old, const unsigned long *new, int bits);
extern int bitmap_bitremap(int oldbit,
return bitmap_parse_user(buf, len, cpumask_bits(dstp), nr_cpumask_bits);
}
+/**
+ * cpumask_parselist_user - extract a cpumask from a user string
+ * @buf: the buffer to extract from
+ * @len: the length of the buffer
+ * @dstp: the cpumask to set.
+ *
+ * Returns -errno, or 0 for success.
+ */
+static inline int cpumask_parselist_user(const char __user *buf, int len,
+ struct cpumask *dstp)
+{
+ return bitmap_parselist_user(buf, len, cpumask_bits(dstp),
+ nr_cpumask_bits);
+}
+
/**
* cpulist_scnprintf - print a cpumask into a string as comma-separated list
* @buf: the buffer to sprintf into
#ifdef CONFIG_SMP
-static int irq_affinity_proc_show(struct seq_file *m, void *v)
+static int show_irq_affinity(int type, struct seq_file *m, void *v)
{
struct irq_desc *desc = irq_to_desc((long)m->private);
const struct cpumask *mask = desc->irq_data.affinity;
if (irqd_is_setaffinity_pending(&desc->irq_data))
mask = desc->pending_mask;
#endif
- seq_cpumask(m, mask);
+ if (type)
+ seq_cpumask_list(m, mask);
+ else
+ seq_cpumask(m, mask);
seq_putc(m, '\n');
return 0;
}
#endif
int no_irq_affinity;
-static ssize_t irq_affinity_proc_write(struct file *file,
+static int irq_affinity_proc_show(struct seq_file *m, void *v)
+{
+ return show_irq_affinity(0, m, v);
+}
+
+static int irq_affinity_list_proc_show(struct seq_file *m, void *v)
+{
+ return show_irq_affinity(1, m, v);
+}
+
+
+static ssize_t write_irq_affinity(int type, struct file *file,
const char __user *buffer, size_t count, loff_t *pos)
{
unsigned int irq = (int)(long)PDE(file->f_path.dentry->d_inode)->data;
if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
return -ENOMEM;
- err = cpumask_parse_user(buffer, count, new_value);
+ if (type)
+ err = cpumask_parselist_user(buffer, count, new_value);
+ else
+ err = cpumask_parse_user(buffer, count, new_value);
if (err)
goto free_cpumask;
return err;
}
+static ssize_t irq_affinity_proc_write(struct file *file,
+ const char __user *buffer, size_t count, loff_t *pos)
+{
+ return write_irq_affinity(0, file, buffer, count, pos);
+}
+
+static ssize_t irq_affinity_list_proc_write(struct file *file,
+ const char __user *buffer, size_t count, loff_t *pos)
+{
+ return write_irq_affinity(1, file, buffer, count, pos);
+}
+
static int irq_affinity_proc_open(struct inode *inode, struct file *file)
{
return single_open(file, irq_affinity_proc_show, PDE(inode)->data);
}
+static int irq_affinity_list_proc_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, irq_affinity_list_proc_show, PDE(inode)->data);
+}
+
static int irq_affinity_hint_proc_open(struct inode *inode, struct file *file)
{
return single_open(file, irq_affinity_hint_proc_show, PDE(inode)->data);
.release = single_release,
};
+static const struct file_operations irq_affinity_list_proc_fops = {
+ .open = irq_affinity_list_proc_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+ .write = irq_affinity_list_proc_write,
+};
+
static int default_affinity_show(struct seq_file *m, void *v)
{
seq_cpumask(m, irq_default_affinity);
proc_create_data("affinity_hint", 0400, desc->dir,
&irq_affinity_hint_proc_fops, (void *)(long)irq);
+ /* create /proc/irq/<irq>/smp_affinity_list */
+ proc_create_data("smp_affinity_list", 0600, desc->dir,
+ &irq_affinity_list_proc_fops, (void *)(long)irq);
+
proc_create_data("node", 0444, desc->dir,
&irq_node_proc_fops, (void *)(long)irq);
#endif
EXPORT_SYMBOL(bitmap_scnlistprintf);
/**
- * bitmap_parselist - convert list format ASCII string to bitmap
+ * __bitmap_parselist - convert list format ASCII string to bitmap
* @bp: read nul-terminated user string from this buffer
+ * @buflen: buffer size in bytes. If string is smaller than this
+ * then it must be terminated with a \0.
+ * @is_user: location of buffer, 0 indicates kernel space
* @maskp: write resulting mask here
* @nmaskbits: number of bits in mask to be written
*
* %-EINVAL: invalid character in string
* %-ERANGE: bit number specified too large for mask
*/
-int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
+static int __bitmap_parselist(const char *buf, unsigned int buflen,
+ int is_user, unsigned long *maskp,
+ int nmaskbits)
{
unsigned a, b;
+ int c, old_c, totaldigits;
+ const char __user *ubuf = buf;
+ int exp_digit, in_range;
+ totaldigits = c = 0;
bitmap_zero(maskp, nmaskbits);
do {
- if (!isdigit(*bp))
- return -EINVAL;
- b = a = simple_strtoul(bp, (char **)&bp, BASEDEC);
- if (*bp == '-') {
- bp++;
- if (!isdigit(*bp))
+ exp_digit = 1;
+ in_range = 0;
+ a = b = 0;
+
+ /* Get the next cpu# or a range of cpu#'s */
+ while (buflen) {
+ old_c = c;
+ if (is_user) {
+ if (__get_user(c, ubuf++))
+ return -EFAULT;
+ } else
+ c = *buf++;
+ buflen--;
+ if (isspace(c))
+ continue;
+
+ /*
+ * If the last character was a space and the current
+ * character isn't '\0', we've got embedded whitespace.
+ * This is a no-no, so throw an error.
+ */
+ if (totaldigits && c && isspace(old_c))
+ return -EINVAL;
+
+ /* A '\0' or a ',' signal the end of a cpu# or range */
+ if (c == '\0' || c == ',')
+ break;
+
+ if (c == '-') {
+ if (exp_digit || in_range)
+ return -EINVAL;
+ b = 0;
+ in_range = 1;
+ exp_digit = 1;
+ continue;
+ }
+
+ if (!isdigit(c))
return -EINVAL;
- b = simple_strtoul(bp, (char **)&bp, BASEDEC);
+
+ b = b * 10 + (c - '0');
+ if (!in_range)
+ a = b;
+ exp_digit = 0;
+ totaldigits++;
}
if (!(a <= b))
return -EINVAL;
set_bit(a, maskp);
a++;
}
- if (*bp == ',')
- bp++;
- } while (*bp != '\0' && *bp != '\n');
+ } while (buflen && c == ',');
return 0;
}
+
+int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
+{
+ char *nl = strchr(bp, '\n');
+ int len;
+
+ if (nl)
+ len = nl - bp;
+ else
+ len = strlen(bp);
+
+ return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
+}
EXPORT_SYMBOL(bitmap_parselist);
+
+/**
+ * bitmap_parselist_user()
+ *
+ * @ubuf: pointer to user buffer containing string.
+ * @ulen: buffer size in bytes. If string is smaller than this
+ * then it must be terminated with a \0.
+ * @maskp: pointer to bitmap array that will contain result.
+ * @nmaskbits: size of bitmap, in bits.
+ *
+ * Wrapper for bitmap_parselist(), providing it with user buffer.
+ *
+ * We cannot have this as an inline function in bitmap.h because it needs
+ * linux/uaccess.h to get the access_ok() declaration and this causes
+ * cyclic dependencies.
+ */
+int bitmap_parselist_user(const char __user *ubuf,
+ unsigned int ulen, unsigned long *maskp,
+ int nmaskbits)
+{
+ if (!access_ok(VERIFY_READ, ubuf, ulen))
+ return -EFAULT;
+ return __bitmap_parselist((const char *)ubuf,
+ ulen, 1, maskp, nmaskbits);
+}
+EXPORT_SYMBOL(bitmap_parselist_user);
+
+
/**
* bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
* @buf: pointer to a bitmap
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