From 3a28fa35d6658703cd26f9c16aaea0eae06afd40 Mon Sep 17 00:00:00 2001 From: "K. Y. Srinivasan" Date: Tue, 8 Apr 2014 18:45:54 -0700 Subject: [PATCH] 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 Reviewed-by: Haiyang Zhang Signed-off-by: Greg Kroah-Hartman --- drivers/hv/channel_mgmt.c | 41 ++++++++++++++++++++++++++++++++++++++++- drivers/hv/connection.c | 24 +++++++++++++++++++++++- drivers/hv/hv.c | 2 ++ drivers/hv/hyperv_vmbus.h | 5 +++++ include/linux/hyperv.h | 5 +++++ 5 files changed, 75 insertions(+), 2 deletions(-) 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 @@ static struct vmbus_channel *alloc_channel(void) 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 @@ static void free_channel(struct vmbus_channel *channel) 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 @@ static void vmbus_process_rescind_offer(struct work_struct *work) 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 @@ static void vmbus_process_offer(struct work_struct *work) work); struct vmbus_channel *channel; bool fnew = true; + bool enq = false; int ret; unsigned long flags; @@ -264,12 +285,22 @@ static void vmbus_process_offer(struct work_struct *work) } } - 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 @@ static void vmbus_process_offer(struct work_struct *work) 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); diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c index df2363e..7f10c15 100644 --- a/drivers/hv/connection.c +++ b/drivers/hv/connection.c @@ -234,6 +234,28 @@ cleanup: return ret; } +/* + * Map the given relid to the corresponding channel based on the + * per-cpu list of channels that have been affinitized to this CPU. + * This will be used in the channel callback path as we can do this + * mapping in a lock-free fashion. + */ +static struct vmbus_channel *pcpu_relid2channel(u32 relid) +{ + struct vmbus_channel *channel; + struct vmbus_channel *found_channel = NULL; + int cpu = smp_processor_id(); + struct list_head *pcpu_head = &hv_context.percpu_list[cpu]; + + list_for_each_entry(channel, pcpu_head, percpu_list) { + if (channel->offermsg.child_relid == relid) { + found_channel = channel; + break; + } + } + + return found_channel; +} /* * relid2channel - Get the channel object given its @@ -285,7 +307,7 @@ static void process_chn_event(u32 relid) * Find the channel based on this relid and invokes the * channel callback to process the event */ - channel = relid2channel(relid); + channel = pcpu_relid2channel(relid); if (!channel) { pr_err("channel not found for relid - %u\n", relid); diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c index bcb4950..edfc848 100644 --- a/drivers/hv/hv.c +++ b/drivers/hv/hv.c @@ -383,6 +383,8 @@ void hv_synic_init(void *arg) */ rdmsrl(HV_X64_MSR_VP_INDEX, vp_index); hv_context.vp_index[cpu] = (u32)vp_index; + + INIT_LIST_HEAD(&hv_context.percpu_list[cpu]); return; } diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h index 860134d..18d1a84 100644 --- a/drivers/hv/hyperv_vmbus.h +++ b/drivers/hv/hyperv_vmbus.h @@ -510,6 +510,11 @@ struct hv_context { * basis. */ struct tasklet_struct *event_dpc[NR_CPUS]; + /* + * To optimize the mapping of relid to channel, maintain + * per-cpu list of the channels based on their CPU affinity. + */ + struct list_head percpu_list[NR_CPUS]; }; extern struct hv_context hv_context; diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index a274e08..08cfaff 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -734,6 +734,11 @@ struct vmbus_channel { * Support per-channel state for use by vmbus drivers. */ void *per_channel_state; + /* + * To support per-cpu lookup mapping of relid to channel, + * link up channels based on their CPU affinity. + */ + struct list_head percpu_list; }; static inline void set_channel_read_state(struct vmbus_channel *c, bool state) -- 2.7.4