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authorAndrea Parri (Microsoft) <parri.andrea@gmail.com>2020-04-06 02:15:11 +0200
committerWei Liu <wei.liu@kernel.org>2020-04-23 13:17:12 +0000
commit8ef4c4abbbcdcd9d4bc0fd9454df03e6dac24b73 (patch)
treeae6ca1adf3b081c09354b785148447504a7cca32 /drivers/hv
parent240ad77cb50d9f0a961fcb0f21e67939cf7a9c04 (diff)
downloadlinux-8ef4c4abbbcdcd9d4bc0fd9454df03e6dac24b73.tar.bz2
Drivers: hv: vmbus: Remove the unused HV_LOCALIZED channel affinity logic
The logic is unused since commit 509879bdb30b8 ("Drivers: hv: Introduce a policy for controlling channel affinity"). This logic assumes that a channel target_cpu doesn't change during the lifetime of a channel, but this assumption is incompatible with the new functionality that allows changing the vCPU a channel will interrupt. Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Link: https://lore.kernel.org/r/20200406001514.19876-9-parri.andrea@gmail.com Reviewed-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Wei Liu <wei.liu@kernel.org>
Diffstat (limited to 'drivers/hv')
-rw-r--r--drivers/hv/channel_mgmt.c105
1 files changed, 25 insertions, 80 deletions
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 2e730f84654b..a19dc28fdf77 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -434,14 +434,6 @@ void hv_process_channel_removal(struct vmbus_channel *channel)
}
/*
- * We need to free the bit for init_vp_index() to work in the case
- * of sub-channel, when we reload drivers like hv_netvsc.
- */
- if (channel->affinity_policy == HV_LOCALIZED)
- cpumask_clear_cpu(channel->target_cpu,
- &primary_channel->alloced_cpus_in_node);
-
- /*
* Upon suspend, an in-use hv_sock channel is marked as "rescinded" and
* the relid is invalidated; after hibernation, when the user-space app
* destroys the channel, the relid is INVALID_RELID, and in this case
@@ -662,20 +654,21 @@ static DEFINE_SPINLOCK(bind_channel_to_cpu_lock);
/*
* Starting with Win8, we can statically distribute the incoming
* channel interrupt load by binding a channel to VCPU.
- * We distribute the interrupt loads to one or more NUMA nodes based on
- * the channel's affinity_policy.
*
* For pre-win8 hosts or non-performance critical channels we assign the
* first CPU in the first NUMA node.
+ *
+ * Starting with win8, performance critical channels will be distributed
+ * evenly among all the available NUMA nodes. Once the node is assigned,
+ * we will assign the CPU based on a simple round robin scheme.
*/
static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
{
- u32 cur_cpu;
bool perf_chn = vmbus_devs[dev_type].perf_device;
- struct vmbus_channel *primary = channel->primary_channel;
- int next_node;
cpumask_var_t available_mask;
struct cpumask *alloced_mask;
+ u32 target_cpu;
+ int numa_node;
if ((vmbus_proto_version == VERSION_WS2008) ||
(vmbus_proto_version == VERSION_WIN7) || (!perf_chn) ||
@@ -693,31 +686,27 @@ static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
return;
}
- spin_lock(&bind_channel_to_cpu_lock);
-
/*
- * Based on the channel affinity policy, we will assign the NUMA
- * nodes.
+ * Serializes the accesses to the global variable next_numa_node_id.
+ * See also the header comment of the spin lock declaration.
*/
+ spin_lock(&bind_channel_to_cpu_lock);
- if ((channel->affinity_policy == HV_BALANCED) || (!primary)) {
- while (true) {
- next_node = next_numa_node_id++;
- if (next_node == nr_node_ids) {
- next_node = next_numa_node_id = 0;
- continue;
- }
- if (cpumask_empty(cpumask_of_node(next_node)))
- continue;
- break;
+ while (true) {
+ numa_node = next_numa_node_id++;
+ if (numa_node == nr_node_ids) {
+ next_numa_node_id = 0;
+ continue;
}
- channel->numa_node = next_node;
- primary = channel;
+ if (cpumask_empty(cpumask_of_node(numa_node)))
+ continue;
+ break;
}
- alloced_mask = &hv_context.hv_numa_map[primary->numa_node];
+ channel->numa_node = numa_node;
+ alloced_mask = &hv_context.hv_numa_map[numa_node];
if (cpumask_weight(alloced_mask) ==
- cpumask_weight(cpumask_of_node(primary->numa_node))) {
+ cpumask_weight(cpumask_of_node(numa_node))) {
/*
* We have cycled through all the CPUs in the node;
* reset the alloced map.
@@ -725,57 +714,13 @@ static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
cpumask_clear(alloced_mask);
}
- cpumask_xor(available_mask, alloced_mask,
- cpumask_of_node(primary->numa_node));
+ cpumask_xor(available_mask, alloced_mask, cpumask_of_node(numa_node));
- cur_cpu = -1;
-
- if (primary->affinity_policy == HV_LOCALIZED) {
- /*
- * Normally Hyper-V host doesn't create more subchannels
- * than there are VCPUs on the node but it is possible when not
- * all present VCPUs on the node are initialized by guest.
- * Clear the alloced_cpus_in_node to start over.
- */
- if (cpumask_equal(&primary->alloced_cpus_in_node,
- cpumask_of_node(primary->numa_node)))
- cpumask_clear(&primary->alloced_cpus_in_node);
- }
-
- while (true) {
- cur_cpu = cpumask_next(cur_cpu, available_mask);
- if (cur_cpu >= nr_cpu_ids) {
- cur_cpu = -1;
- cpumask_copy(available_mask,
- cpumask_of_node(primary->numa_node));
- continue;
- }
-
- if (primary->affinity_policy == HV_LOCALIZED) {
- /*
- * NOTE: in the case of sub-channel, we clear the
- * sub-channel related bit(s) in
- * primary->alloced_cpus_in_node in
- * hv_process_channel_removal(), so when we
- * reload drivers like hv_netvsc in SMP guest, here
- * we're able to re-allocate
- * bit from primary->alloced_cpus_in_node.
- */
- if (!cpumask_test_cpu(cur_cpu,
- &primary->alloced_cpus_in_node)) {
- cpumask_set_cpu(cur_cpu,
- &primary->alloced_cpus_in_node);
- cpumask_set_cpu(cur_cpu, alloced_mask);
- break;
- }
- } else {
- cpumask_set_cpu(cur_cpu, alloced_mask);
- break;
- }
- }
+ target_cpu = cpumask_first(available_mask);
+ cpumask_set_cpu(target_cpu, alloced_mask);
- channel->target_cpu = cur_cpu;
- channel->target_vp = hv_cpu_number_to_vp_number(cur_cpu);
+ channel->target_cpu = target_cpu;
+ channel->target_vp = hv_cpu_number_to_vp_number(target_cpu);
spin_unlock(&bind_channel_to_cpu_lock);