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Date: Fri, 4 Jan 2008 23:38:52 +0800
From: "rae l" <crquan@...il.com>
To: "Paul Jackson" <pj@....com>
Cc: akpm@...ux-foundation.org, viro@...iv.linux.org.uk,
torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
emdow@...ibm.com
Subject: Re: [PATCH] PROC_FS: get and set the smp affinity of tasks by read-write /proc/<pid>/smp_affinity
>From d2be88406fdc1d28a7cf0b1a13ca761d625820a5 Mon Sep 17 00:00:00 2001
From: Denis Cheng <crquan@...il.com>
Date: Fri, 4 Jan 2008 14:50:54 +0800
Subject: [PATCH] PROC_FS: get and set the smp affinity of tasks by
read-write /proc/<pid>/smp_affinity
this adds a read-write /proc/<pid>/smp_affinity entry,
just like what /proc/irq/<irq>/smp_affinity does,
so now we can get and set the affinity of tasks by procfs,
this is especially useful used in shell scripts.
this also adds a read-write /proc/<pid>/tasks/<tid>/smp_affinity
for the same purpose.
Cc: Eli M Dow <emdow@...ibm.com>
Signed-off-by: Denis Cheng <crquan@...il.com>
---
length check copied from kernel/irq/proc.c, now 'page' buffer couldn't
be overrun,
Another way, although Documentation/filesystems/proc.txt is heavily outdated,
I'll add introduction of smp_affinity.
fs/proc/base.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 65 insertions(+), 0 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 7411bfb..d768d66 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1083,6 +1083,65 @@ static const struct file_operations
proc_pid_sched_operations = {
#endif
+#ifdef CONFIG_SMP
+static ssize_t smp_affinity_read(struct file *file,
+ char __user *buf, size_t count, loff_t *ppos)
+{
+ cpumask_t mask;
+ char *page;
+ ssize_t length;
+ pid_t pid = pid_nr(proc_pid(file->f_dentry->d_inode));
+
+ length = sched_getaffinity(pid, &mask);
+ if (length < 0)
+ return length;
+
+ if (count > PROC_BLOCK_SIZE)
+ count = PROC_BLOCK_SIZE;
+
+ page = (char *)__get_free_page(GFP_TEMPORARY);
+ if (!page) {
+ length = -ENOMEM;
+ goto out;
+ }
+
+ length = cpumask_scnprintf(page, count, mask);
+ if (count - length < 2) {
+ length = -EINVAL;
+ goto out_free_page;
+ }
+ length += sprintf(page + length, "\n");
+ length = simple_read_from_buffer(buf, count, ppos, page, length);
+
+out_free_page:
+ free_page((unsigned long)page);
+out:
+ return length;
+}
+
+static ssize_t smp_affinity_write(struct file *file,
+ const char __user *buf, size_t count, loff_t *ppos)
+{
+ cpumask_t mask;
+ int ret;
+ pid_t pid = pid_nr(proc_pid(file->f_dentry->d_inode));
+
+ ret = cpumask_parse_user(buf, count, mask);
+ if (ret < 0)
+ return ret;
+ ret = sched_setaffinity(pid, mask);
+ if (ret < 0)
+ return ret;
+
+ return count;
+}
+
+static const struct file_operations proc_smp_affinity_operations = {
+ .read = smp_affinity_read,
+ .write = smp_affinity_write,
+};
+#endif
+
static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct inode *inode = dentry->d_inode;
@@ -2230,6 +2289,9 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_SCHEDSTATS
INF("schedstat", S_IRUGO, pid_schedstat),
#endif
+#ifdef CONFIG_SMP
+ REG("smp_affinity", S_IRUGO|S_IWUSR, smp_affinity),
+#endif
#ifdef CONFIG_PROC_PID_CPUSET
REG("cpuset", S_IRUGO, cpuset),
#endif
@@ -2555,6 +2617,9 @@ static const struct pid_entry tid_base_stuff[] = {
#ifdef CONFIG_SCHEDSTATS
INF("schedstat", S_IRUGO, pid_schedstat),
#endif
+#ifdef CONFIG_SMP
+ REG("smp_affinity", S_IRUGO|S_IWUSR, smp_affinity),
+#endif
#ifdef CONFIG_PROC_PID_CPUSET
REG("cpuset", S_IRUGO, cpuset),
#endif
--
1.5.3.5
--
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