[PATCH 4/4] Add /proc files to expose per-mm pgcollapse stats

[Alex Thorlton]

This patch adds a /proc file to read out the information that we've added to the
task_struct.  I'll need to split the information out to separate files, probably
in a subdirectory, change a few of the files to allow us to modify their values,
and it will need appropriate locks.

Signed-off-by: Alex Thorlton <athorlton@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Bob Liu <lliubbo@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx

---
 fs/proc/base.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 772efa4..a6603e5 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2466,6 +2466,25 @@ static const struct file_operations proc_projid_map_operations = {
 };
 #endif /* CONFIG_USER_NS */
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+int proc_pgcollapse_show(struct seq_file *m, struct pid_namespace *ns,
+		     struct pid *pid, struct task_struct *tsk)
+{
+	/* need locks here */
+	seq_printf(m, "pages_to_scan: %u\n", tsk->pgcollapse_pages_to_scan);
+	seq_printf(m, "pages_collapsed: %u\n", tsk->pgcollapse_pages_collapsed);
+	seq_printf(m, "full_scans: %u\n", tsk->pgcollapse_full_scans);
+	seq_printf(m, "scan_sleep_millisecs: %u\n",
+		   tsk->pgcollapse_scan_sleep_millisecs);
+	seq_printf(m, "alloc_sleep_millisecs: %u\n",
+		   tsk->pgcollapse_alloc_sleep_millisecs);
+	seq_printf(m, "last_scan: %lu\n", tsk->pgcollapse_last_scan);
+	seq_printf(m, "scan_address: 0x%0lx\n", tsk->pgcollapse_scan_address);
+
+	return 0;
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
 static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
 				struct pid *pid, struct task_struct *task)
 {
@@ -2576,6 +2595,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_CHECKPOINT_RESTORE
 	REG("timers",	  S_IRUGO, proc_timers_operations),
 #endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	ONE("pgcollapse", S_IRUGO, proc_pgcollapse_show),
+#endif
 };
 
 static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
@@ -2914,6 +2936,9 @@ static const struct pid_entry tid_base_stuff[] = {
 	REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),
 	REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
 #endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	ONE("pgcollapse", S_IRUGO, proc_pgcollapse_show),
+#endif
 };
 
 static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)
-- 
1.7.12.4

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