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Commit 9f01ec53 authored by K. Y. Srinivasan's avatar K. Y. Srinivasan Committed by Greg Kroah-Hartman
Browse files

Drivers: hv: vmbus: Improve the CPU affiliation for channels 



The current code tracks the assigned CPUs within a NUMA node in the context of
the primary channel. So, if we have a VM with a single NUMA node with 8 VCPUs, we may
end up unevenly distributing the channel load. Fix the issue by tracking affiliations
globally.

Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 35464483

drivers/hv/channel_mgmt.c

+6 −5
Original line number Diff line number Diff line
@@ -392,6 +392,7 @@ static void init_vp_index(struct vmbus_channel *channel, const uuid_le *type_gui 
	struct vmbus_channel *primary = channel->primary_channel;

	int next_node;

	struct cpumask available_mask;

	struct cpumask *alloced_mask;



	for (i = IDE; i < MAX_PERF_CHN; i++) {

		if (!memcmp(type_guid->b, hp_devs[i].guid,
@@ -409,7 +410,6 @@ static void init_vp_index(struct vmbus_channel *channel, const uuid_le *type_gui 
		 * channel, bind it to cpu 0.

		 */

		channel->numa_node = 0;

		cpumask_set_cpu(0, &channel->alloced_cpus_in_node);

		channel->target_cpu = 0;

		channel->target_vp = hv_context.vp_index[0];

		return;
@@ -434,21 +434,22 @@ static void init_vp_index(struct vmbus_channel *channel, const uuid_le *type_gui 
		channel->numa_node = next_node;

		primary = channel;

	}

	alloced_mask = &hv_context.hv_numa_map[primary->numa_node];



	if (cpumask_weight(&primary->alloced_cpus_in_node) ==

	if (cpumask_weight(alloced_mask) ==

	    cpumask_weight(cpumask_of_node(primary->numa_node))) {

		/*

		 * We have cycled through all the CPUs in the node;

		 * reset the alloced map.

		 */

		cpumask_clear(&primary->alloced_cpus_in_node);

		cpumask_clear(alloced_mask);

	}



	cpumask_xor(&available_mask, &primary->alloced_cpus_in_node,

	cpumask_xor(&available_mask, alloced_mask,

		    cpumask_of_node(primary->numa_node));



	cur_cpu = cpumask_next(-1, &available_mask);

	cpumask_set_cpu(cur_cpu, &primary->alloced_cpus_in_node);

	cpumask_set_cpu(cur_cpu, alloced_mask);



	channel->target_cpu = cur_cpu;

	channel->target_vp = hv_context.vp_index[cur_cpu];

drivers/hv/hv.c

+9 −0
Original line number Diff line number Diff line
@@ -332,6 +332,13 @@ int hv_synic_alloc(void) 
	size_t ced_size = sizeof(struct clock_event_device);

	int cpu;



	hv_context.hv_numa_map = kzalloc(sizeof(struct cpumask) * nr_node_ids,

					 GFP_ATOMIC);

	if (hv_context.hv_numa_map == NULL) {

		pr_err("Unable to allocate NUMA map\n");

		goto err;

	}



	for_each_online_cpu(cpu) {

		hv_context.event_dpc[cpu] = kmalloc(size, GFP_ATOMIC);

		if (hv_context.event_dpc[cpu] == NULL) {
@@ -345,6 +352,7 @@ int hv_synic_alloc(void) 
			pr_err("Unable to allocate clock event device\n");

			goto err;

		}



		hv_init_clockevent_device(hv_context.clk_evt[cpu], cpu);



		hv_context.synic_message_page[cpu] =
@@ -393,6 +401,7 @@ void hv_synic_free(void) 
{

	int cpu;



	kfree(hv_context.hv_numa_map);

	for_each_online_cpu(cpu)

		hv_synic_free_cpu(cpu);

}

drivers/hv/hyperv_vmbus.h

+5 −0
Original line number Diff line number Diff line
@@ -551,6 +551,11 @@ struct hv_context { 
	 * Support PV clockevent device.

	 */

	struct clock_event_device *clk_evt[NR_CPUS];

	/*

	 * To manage allocations in a NUMA node.

	 * Array indexed by numa node ID.

	 */

	struct cpumask *hv_numa_map;

};



extern struct hv_context hv_context;

include/linux/hyperv.h

+0 −1
Original line number Diff line number Diff line
@@ -699,7 +699,6 @@ struct vmbus_channel { 
	/*

	 * State to manage the CPU affiliation of channels.

	 */

	struct cpumask alloced_cpus_in_node;

	int numa_node;

	/*

	 * Support for sub-channels. For high performance devices,