[PATCH v2 09/10] nvme/mdev - Add inline performance measurments

[Maxim Levitsky]

This code might not be needed to be merged in the final version

Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
---
 drivers/nvme/mdev/instance.c | 62 ++++++++++++++++++++++++++++++++++++
 drivers/nvme/mdev/io.c       | 21 ++++++++++++
 drivers/nvme/mdev/irq.c      |  6 ++++
 drivers/nvme/mdev/priv.h     | 13 ++++++++
 drivers/nvme/mdev/vctrl.c    |  3 ++
 5 files changed, 105 insertions(+)

diff --git a/drivers/nvme/mdev/instance.c b/drivers/nvme/mdev/instance.c
index 0e5ba5a9269f..d692b2bf2ef2 100644
--- a/drivers/nvme/mdev/instance.c
+++ b/drivers/nvme/mdev/instance.c
@@ -771,6 +771,62 @@ static struct attribute *nvme_mdev_dev_settings_atttributes[] = {
 	NULL
 };
 
+/* show perf stats */
+static ssize_t stats_show(struct device *dev,
+			  struct device_attribute *attr, char *buf)
+{
+	struct nvme_mdev_vctrl *vctrl = dev_to_vctrl(dev);
+	struct nvme_mdev_perf *perf;
+
+	if (!vctrl)
+		return -ENODEV;
+
+	perf = &vctrl->perf;
+
+	return sprintf(buf,
+		"%u %llu %llu %llu %llu %llu %llu\n",
+
+		tsc_khz,
+
+		perf->cmds_started,
+		perf->cycles_send_to_hw,
+
+		perf->cmds_complete,
+		perf->cycles_receive_from_hw,
+
+		perf->interrupts_sent,
+		perf->cycles_irq_delivery);
+}
+
+/* clear the perf stats */
+static ssize_t stats_store(struct device *dev,
+			   struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	bool val;
+	int ret;
+	struct nvme_mdev_vctrl *vctrl = dev_to_vctrl(dev);
+
+	if (!vctrl)
+		return -ENODEV;
+	ret = kstrtobool(buf, &val);
+	if (ret)
+		return ret;
+
+	if (!val)
+		return -EINVAL;
+
+	memset(&vctrl->perf, 0, sizeof(vctrl->perf));
+	return count;
+}
+
+static DEVICE_ATTR_RW(stats);
+
+static struct attribute *nvme_mdev_dev_debug_attributes[] = {
+	&dev_attr_stats.attr,
+	NULL
+};
+
 static const struct attribute_group nvme_mdev_ns_attr_group = {
 	.name = "namespaces",
 	.attrs = nvme_mdev_dev_ns_atttributes,
@@ -781,9 +837,15 @@ static const struct attribute_group nvme_mdev_setting_attr_group = {
 	.attrs = nvme_mdev_dev_settings_atttributes,
 };
 
+static const struct attribute_group nvme_mdev_debug_attr_group = {
+	.name = "debug",
+	.attrs = nvme_mdev_dev_debug_attributes,
+};
+
 static const struct attribute_group *nvme_mdev_dev_attributte_groups[] = {
 	&nvme_mdev_ns_attr_group,
 	&nvme_mdev_setting_attr_group,
+	&nvme_mdev_debug_attr_group,
 	NULL,
 };
 
diff --git a/drivers/nvme/mdev/io.c b/drivers/nvme/mdev/io.c
index 59837540fec2..39550d0e3649 100644
--- a/drivers/nvme/mdev/io.c
+++ b/drivers/nvme/mdev/io.c
@@ -9,6 +9,7 @@
 #include <linux/nvme.h>
 #include <linux/timekeeping.h>
 #include <linux/ktime.h>
+#include <asm/msr.h>
 #include "priv.h"
 
 
@@ -251,6 +252,9 @@ static bool nvme_mdev_io_process_sq(struct io_ctx *ctx, u16 sqid)
 	struct nvme_vsq *vsq = &ctx->vctrl->vsqs[sqid];
 	u16 ucid;
 	int ret;
+	unsigned long long c1, c2;
+
+	c1 = rdtsc();
 
 	/* If host queue is full, we can't process a command
 	 * as a command will likely result in passthrough
@@ -289,6 +293,12 @@ static bool nvme_mdev_io_process_sq(struct io_ctx *ctx, u16 sqid)
 
 		nvme_mdev_vsq_cmd_done_io(ctx->vctrl, sqid, ucid, ret);
 	}
+
+	c2 = rdtsc();
+
+	ctx->vctrl->perf.cmds_started++;
+	ctx->vctrl->perf.cycles_send_to_hw += (c2 - c1);
+
 	return true;
 }
 
@@ -304,6 +314,10 @@ static int nvme_mdev_io_process_hwq(struct io_ctx *ctx, u16 hwq)
 	int n, i;
 	struct nvme_ext_cmd_result res[16];
 
+	unsigned long long c1, c2;
+
+	c1 = rdtsc();
+
 	/* process the completions from the hardware */
 	n = nvme_mdev_hctrl_hq_poll(ctx->hctrl, hwq, res, 16);
 	if (n == -1)
@@ -321,6 +335,13 @@ static int nvme_mdev_io_process_hwq(struct io_ctx *ctx, u16 hwq)
 
 		nvme_mdev_vsq_cmd_done_io(ctx->vctrl, qid, cid, status);
 	}
+
+	if (n > 0) {
+		c2 = rdtsc();
+		ctx->vctrl->perf.cmds_complete += n;
+		ctx->vctrl->perf.cycles_receive_from_hw += (c2 - c1);
+	}
+
 	return n;
 }
 
diff --git a/drivers/nvme/mdev/irq.c b/drivers/nvme/mdev/irq.c
index 5809cdb4d84c..b6010a69b584 100644
--- a/drivers/nvme/mdev/irq.c
+++ b/drivers/nvme/mdev/irq.c
@@ -9,6 +9,7 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include "priv.h"
+#include <asm/msr.h>
 
 /* Setup the interrupt subsystem */
 void nvme_mdev_irqs_setup(struct nvme_mdev_vctrl *vctrl)
@@ -253,12 +254,17 @@ void nvme_mdev_irq_cond_trigger(struct nvme_mdev_vctrl *vctrl,
 				unsigned int index)
 {
 	struct nvme_mdev_user_irq *irq = &vctrl->irqs.vecs[index];
+	unsigned long long c1, c2;
 
 	if (irq->irq_pending_cnt == 0)
 		return;
 
 	if (!nvme_mdev_irq_coalesce(vctrl, irq)) {
+		vctrl->perf.interrupts_sent++;
+		c1 = rdtsc();
 		nvme_mdev_irq_trigger(vctrl, index);
+		c2 = rdtsc();
 		nvme_mdev_irq_clear(vctrl, index);
+		vctrl->perf.cycles_irq_delivery += (c2 - c1);
 	}
 }
diff --git a/drivers/nvme/mdev/priv.h b/drivers/nvme/mdev/priv.h
index 9f65e46c1ab2..a11a1842957d 100644
--- a/drivers/nvme/mdev/priv.h
+++ b/drivers/nvme/mdev/priv.h
@@ -245,6 +245,17 @@ struct nvme_mdev_io_region {
 	unsigned int mmap_area_size;
 };
 
+struct nvme_mdev_perf {
+	/* number of IO commands received */
+	unsigned long long cmds_started;
+	unsigned long long cmds_complete;
+	unsigned long long interrupts_sent;
+
+	unsigned long long cycles_send_to_hw;
+	unsigned long long cycles_receive_from_hw;
+	unsigned long long cycles_irq_delivery;
+};
+
 /*Virtual NVME controller state */
 struct nvme_mdev_vctrl {
 	struct kref ref;
@@ -301,6 +312,8 @@ struct nvme_mdev_vctrl {
 	char serial[9];
 
 	bool vctrl_paused; /* true when the host device paused our IO */
+
+	struct nvme_mdev_perf perf;
 };
 
 /* mdev instance type*/
diff --git a/drivers/nvme/mdev/vctrl.c b/drivers/nvme/mdev/vctrl.c
index 87bc7c435c0c..d23b543dfd52 100644
--- a/drivers/nvme/mdev/vctrl.c
+++ b/drivers/nvme/mdev/vctrl.c
@@ -242,6 +242,9 @@ int nvme_mdev_vctrl_open(struct nvme_mdev_vctrl *vctrl)
 
 	nvme_mdev_mmio_open(vctrl);
 	vctrl->inuse = true;
+
+	memset(&vctrl->perf, 0, sizeof(vctrl->perf));
+
 out:
 	mutex_unlock(&vctrl->lock);
 	return ret;
-- 
2.17.2