[dpdk-dev] [PATCH 2/4] bus/vmbus: add host latency tuning function
Stephen Hemminger
stephen at networkplumber.org
Thu Aug 9 19:50:06 CEST 2018
Add vmbus API to allow tuning the scan interval on the host side.
Signed-off-by: Stephen Hemminger <sthemmin at microsoft.com>
---
drivers/bus/vmbus/rte_bus_vmbus.h | 15 ++++++++++++
drivers/bus/vmbus/rte_bus_vmbus_version.map | 1 +
drivers/bus/vmbus/vmbus_channel.c | 26 +++++++++++++++++++++
3 files changed, 42 insertions(+)
diff --git a/drivers/bus/vmbus/rte_bus_vmbus.h b/drivers/bus/vmbus/rte_bus_vmbus.h
index 4a2c1f6fd918..2839fef5b27a 100644
--- a/drivers/bus/vmbus/rte_bus_vmbus.h
+++ b/drivers/bus/vmbus/rte_bus_vmbus.h
@@ -364,6 +364,21 @@ void rte_vmbus_chan_signal_read(struct vmbus_channel *chan, uint32_t bytes_read)
*/
uint16_t rte_vmbus_sub_channel_index(const struct vmbus_channel *chan);
+/**
+ * Set the host monitor latency hint
+ *
+ * @param dev
+ * VMBUS device
+ * @param chan
+ * Pointer to vmbus_channel structure.
+ * @param latency
+ * Approximate wait period between hypervisor examinations of
+ * the trigger page (in nanoseconds).
+ */
+void rte_vmbus_set_latency(const struct rte_vmbus_device *dev,
+ const struct vmbus_channel *chan,
+ uint32_t latency);
+
/**
* Register a VMBUS driver.
*
diff --git a/drivers/bus/vmbus/rte_bus_vmbus_version.map b/drivers/bus/vmbus/rte_bus_vmbus_version.map
index dabb9203104b..5b01ff30d7b0 100644
--- a/drivers/bus/vmbus/rte_bus_vmbus_version.map
+++ b/drivers/bus/vmbus/rte_bus_vmbus_version.map
@@ -20,6 +20,7 @@ DPDK_18.08 {
rte_vmbus_probe;
rte_vmbus_register;
rte_vmbus_scan;
+ rte_vmbus_set_latency;
rte_vmbus_sub_channel_index;
rte_vmbus_subchan_open;
rte_vmbus_unmap_device;
diff --git a/drivers/bus/vmbus/vmbus_channel.c b/drivers/bus/vmbus/vmbus_channel.c
index cc5f3e8379a5..bd14c0662b46 100644
--- a/drivers/bus/vmbus/vmbus_channel.c
+++ b/drivers/bus/vmbus/vmbus_channel.c
@@ -59,6 +59,32 @@ vmbus_set_event(const struct rte_vmbus_device *dev,
vmbus_set_monitor(dev, chan->monitor_id);
}
+/*
+ * Set the wait between when hypervisor examines the trigger.
+ */
+void
+rte_vmbus_set_latency(const struct rte_vmbus_device *dev,
+ const struct vmbus_channel *chan,
+ uint32_t latency)
+{
+ uint32_t trig_idx = chan->monitor_id / VMBUS_MONTRIG_LEN;
+ uint32_t trig_offs = chan->monitor_id % VMBUS_MONTRIG_LEN;
+
+ if (latency >= UINT16_MAX * 100) {
+ VMBUS_LOG(ERR, "invalid latency value %u", latency);
+ return;
+ }
+
+ if (trig_idx >= VMBUS_MONTRIGS_MAX) {
+ VMBUS_LOG(ERR, "invalid monitor trigger %u",
+ trig_idx);
+ return;
+ }
+
+ /* Host value is expressed in 100 nanosecond units */
+ dev->monitor_page->lat[trig_idx][trig_offs] = latency / 100;
+}
+
/*
* Notify host that there are data pending on our TX bufring.
*
--
2.18.0
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