Drivers: hv: vmbus: Implement per-CPU mapping of relid to channel
Currently the mapping of the relID to channel is done under the protection of a
single spin lock. Starting with ws2012, each channel is bound to a specific VCPU
in the guest. Use this binding to eliminate the spin lock by setting up
per-cpu state for mapping relId to the channel.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 6f7fdd9..6c8b032c 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -149,6 +149,7 @@
spin_lock_init(&channel->sc_lock);
INIT_LIST_HEAD(&channel->sc_list);
+ INIT_LIST_HEAD(&channel->percpu_list);
channel->controlwq = create_workqueue("hv_vmbus_ctl");
if (!channel->controlwq) {
@@ -188,7 +189,20 @@
queue_work(vmbus_connection.work_queue, &channel->work);
}
+static void percpu_channel_enq(void *arg)
+{
+ struct vmbus_channel *channel = arg;
+ int cpu = smp_processor_id();
+ list_add_tail(&channel->percpu_list, &hv_context.percpu_list[cpu]);
+}
+
+static void percpu_channel_deq(void *arg)
+{
+ struct vmbus_channel *channel = arg;
+
+ list_del(&channel->percpu_list);
+}
/*
* vmbus_process_rescind_offer -
@@ -210,6 +224,12 @@
msg.header.msgtype = CHANNELMSG_RELID_RELEASED;
vmbus_post_msg(&msg, sizeof(struct vmbus_channel_relid_released));
+ if (channel->target_cpu != smp_processor_id())
+ smp_call_function_single(channel->target_cpu,
+ percpu_channel_deq, channel, true);
+ else
+ percpu_channel_deq(channel);
+
if (channel->primary_channel == NULL) {
spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
list_del(&channel->listentry);
@@ -245,6 +265,7 @@
work);
struct vmbus_channel *channel;
bool fnew = true;
+ bool enq = false;
int ret;
unsigned long flags;
@@ -264,12 +285,22 @@
}
}
- if (fnew)
+ if (fnew) {
list_add_tail(&newchannel->listentry,
&vmbus_connection.chn_list);
+ enq = true;
+ }
spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
+ if (enq) {
+ if (newchannel->target_cpu != smp_processor_id())
+ smp_call_function_single(newchannel->target_cpu,
+ percpu_channel_enq,
+ newchannel, true);
+ else
+ percpu_channel_enq(newchannel);
+ }
if (!fnew) {
/*
* Check to see if this is a sub-channel.
@@ -282,6 +313,14 @@
spin_lock_irqsave(&channel->sc_lock, flags);
list_add_tail(&newchannel->sc_list, &channel->sc_list);
spin_unlock_irqrestore(&channel->sc_lock, flags);
+
+ if (newchannel->target_cpu != smp_processor_id())
+ smp_call_function_single(newchannel->target_cpu,
+ percpu_channel_enq,
+ newchannel, true);
+ else
+ percpu_channel_enq(newchannel);
+
newchannel->state = CHANNEL_OPEN_STATE;
if (channel->sc_creation_callback != NULL)
channel->sc_creation_callback(newchannel);
