[Devel] [PATCH RHEL7 COMMIT] ve/page_alloc, kstat: account allocation latencies per-task

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-693.17.1.vz7.43.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.17.1.vz7.43.6
------>
commit 6d9a9210395e1f7573f5da6be18a3362f52eea8c
Author: Andrey Ryabinin <aryabinin at virtuozzo.com>
Date:   Thu Feb 15 19:02:33 2018 +0300

    ve/page_alloc, kstat: account allocation latencies per-task
    
    Vstorage wants per-process allocation latencies:
    
     - total accumulated latency (total time spent inside the kernel allocator)
     - total alloc attempts (so that average latency can be calculated)
    
    This adds /proc/<pid>/vz_latency file which outputs the numbers:
    
    Type                   Total_lat                Calls
    allocatomic:                    0                 1334
    alloc:                    8000000                36643
    allocmp:                        0                  919
    
    https://jira.sw.ru/browse/PSBM-81395
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
    
    Cc: Pavel Borzenkov <pborzenkov at virtuozzo.com>
---
 fs/proc/base.c        | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/sched.h |  4 ++++
 mm/page_alloc.c       |  5 +++++
 3 files changed, 60 insertions(+)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 4c29a4f026ab..5646a351c076 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -55,6 +55,7 @@
 #include <linux/stat.h>
 #include <linux/task_io_accounting_ops.h>
 #include <linux/init.h>
+#include <linux/kstat.h>
 #include <linux/capability.h>
 #include <linux/file.h>
 #include <linux/fdtable.h>
@@ -574,6 +575,53 @@ static const struct file_operations proc_lstats_operations = {
 
 #endif
 
+#ifdef CONFIG_VE
+static void lastlat_seq_show(struct seq_file *m,
+		const char *name,
+		struct kstat_lat_snap_struct *snap)
+{
+	seq_printf(m, "%-12s %20Lu %20lu\n", name,
+			snap->totlat, snap->count);
+}
+
+static int vz_lat_show_proc(struct seq_file *m, void *v)
+{
+	int i;
+	struct inode *inode = m->private;
+	struct task_struct *task = get_proc_task(inode);
+	static const char *alloc_descr[] = {
+		"allocatomic:",
+		"alloc:",
+		"allocmp:",
+	};
+	static const int alloc_types[] = {
+		KSTAT_ALLOCSTAT_ATOMIC,
+		KSTAT_ALLOCSTAT_LOW,
+		KSTAT_ALLOCSTAT_LOW_MP,
+	};
+
+	seq_printf(m, "%-11s %20s %20s\n",
+			"Type", "Total_lat", "Calls");
+
+	for (i = 0; i < ARRAY_SIZE(alloc_types); i++)
+		lastlat_seq_show(m, alloc_descr[i],
+				&task->alloc_lat[alloc_types[i]]);
+	return 0;
+}
+
+static int vz_lat_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, vz_lat_show_proc, inode);
+}
+
+static const struct file_operations proc_vz_lat_operations = {
+	.open		= vz_lat_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+#endif
+
 #ifdef CONFIG_CGROUPS
 static int cgroup_open(struct inode *inode, struct file *file)
 {
@@ -3011,6 +3059,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 	REG("timers",	  S_IRUGO, proc_timers_operations),
 	REG("aio",	  S_IRUGO|S_IWUSR, proc_aio_operations),
 #endif
+#ifdef CONFIG_VE
+	REG("vz_latency", S_IRUGO, proc_vz_lat_operations),
+#endif
 };
 
 static int proc_tgid_base_readdir(struct file * filp,
diff --git a/include/linux/sched.h b/include/linux/sched.h
index cc52094b4e97..1595be347b6d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -30,6 +30,7 @@ struct sched_param {
 
 #include <linux/smp.h>
 #include <linux/sem.h>
+#include <linux/kstat.h>
 #include <linux/signal.h>
 #include <linux/compiler.h>
 #include <linux/completion.h>
@@ -1833,6 +1834,9 @@ struct task_struct {
 #ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
 	struct tlbflush_unmap_batch tlb_ubc;
 #endif
+#ifdef CONFIG_VE
+	struct kstat_lat_snap_struct alloc_lat[KSTAT_ALLOCSTAT_NR];
+#endif
 #if defined(CONFIG_FUNCTION_GRAPH_TRACER) && defined(CONFIG_S390)
 	/* Index of current stored address in ret_stack */
 	int curr_ret_stack;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f08ddeb77b82..fed5d879179f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3156,8 +3156,13 @@ static void __alloc_collect_stats(gfp_t gfp_mask, unsigned int order,
 	local_irq_save(flags);
 	cpu = smp_processor_id();
 	KSTAT_LAT_PCPU_ADD(&kstat_glob.alloc_lat[ind], time);
+
+	current->alloc_lat[ind].totlat += time;
+	current->alloc_lat[ind].count++;
+
 	if (!page)
 		kstat_glob.alloc_fails[cpu][ind]++;
+
 	local_irq_restore(flags);
 #endif
 }