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vmbus: change to per channel tasklet 

Make the event handling tasklet per channel rather than per-cpu.
This allows for better fairness when getting lots of data on the same
cpu.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Stephen Hemminger 2017-02-11 23:02:20 -07:00 committed by Greg Kroah-Hartman
parent 37cdd991fa
commit 631e63a9f3
7 changed files with 64 additions and 96 deletions
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2
drivers/hv/channel.c
View File

@ -530,7 +530,7 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
int ret;
/*
* process_chn_event(), running in the tasklet, can race
* vmbus_on_event(), running in the tasklet, can race
* with vmbus_close_internal() in the case of SMP guest, e.g., when
* the former is accessing channel->inbound.ring_buffer, the latter
* could be freeing the ring_buffer pages.

16
drivers/hv/channel_mgmt.c
View File

@ -339,6 +339,9 @@ static struct vmbus_channel *alloc_channel(void)
INIT_LIST_HEAD(&channel->sc_list);
INIT_LIST_HEAD(&channel->percpu_list);
tasklet_init(&channel->callback_event,
vmbus_on_event, (unsigned long)channel);
return channel;
}
@ -347,6 +350,7 @@ static struct vmbus_channel *alloc_channel(void)
*/
static void free_channel(struct vmbus_channel *channel)
{
tasklet_kill(&channel->callback_event);
kfree(channel);
}
@ -380,21 +384,15 @@ static void vmbus_release_relid(u32 relid)
void hv_event_tasklet_disable(struct vmbus_channel *channel)
{
struct hv_per_cpu_context *hv_cpu;
hv_cpu = per_cpu_ptr(hv_context.cpu_context, channel->target_cpu);
tasklet_disable(&hv_cpu->event_dpc);
tasklet_disable(&channel->callback_event);
}
void hv_event_tasklet_enable(struct vmbus_channel *channel)
{
struct hv_per_cpu_context *hv_cpu;
hv_cpu = per_cpu_ptr(hv_context.cpu_context, channel->target_cpu);
tasklet_enable(&hv_cpu->event_dpc);
tasklet_enable(&channel->callback_event);
/* In case there is any pending event */
tasklet_schedule(&hv_cpu->event_dpc);
tasklet_schedule(&channel->callback_event);
}
void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid)

78
drivers/hv/connection.c
View File

@ -259,29 +259,6 @@ void vmbus_disconnect(void)
vmbus_connection.monitor_pages[1] = NULL;
}
/*
* 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 hv_per_cpu_context *hv_cpu
= this_cpu_ptr(hv_context.cpu_context);
struct vmbus_channel *found_channel = NULL;
struct vmbus_channel *channel;
list_for_each_entry(channel, &hv_cpu->chan_list, percpu_list) {
if (channel->offermsg.child_relid == relid) {
found_channel = channel;
break;
}
}
return found_channel;
}
/*
* relid2channel - Get the channel object given its
* child relative id (ie channel id)
@ -318,24 +295,15 @@ struct vmbus_channel *relid2channel(u32 relid)
}
/*
* process_chn_event - Process a channel event notification
* vmbus_on_event - Process a channel event notification
*/
static void process_chn_event(u32 relid)
void vmbus_on_event(unsigned long data)
{
struct vmbus_channel *channel;
struct vmbus_channel *channel = (void *) data;
void *arg;
bool read_state;
u32 bytes_to_read;
/*
* Find the channel based on this relid and invokes the
* channel callback to process the event
*/
channel = pcpu_relid2channel(relid);
if (!channel)
return;
/*
* A channel once created is persistent even when there
* is no driver handling the device. An unloading driver
@ -344,7 +312,6 @@ static void process_chn_event(u32 relid)
* Thus, checking and invoking the driver specific callback takes
* care of orderly unloading of the driver.
*/
if (channel->onchannel_callback != NULL) {
arg = channel->channel_callback_context;
read_state = channel->batched_reading;
@ -372,45 +339,6 @@ static void process_chn_event(u32 relid)
}
}
/*
* vmbus_on_event - Handler for events
*/
void vmbus_on_event(unsigned long data)
{
struct hv_per_cpu_context *hv_cpu = (void *)data;
unsigned long *recv_int_page;
u32 maxbits, relid;
if (vmbus_proto_version < VERSION_WIN8) {
maxbits = MAX_NUM_CHANNELS_SUPPORTED;
recv_int_page = vmbus_connection.recv_int_page;
} else {
/*
* When the host is win8 and beyond, the event page
* can be directly checked to get the id of the channel
* that has the interrupt pending.
*/
void *page_addr = hv_cpu->synic_event_page;
union hv_synic_event_flags *event
= (union hv_synic_event_flags *)page_addr +
VMBUS_MESSAGE_SINT;
maxbits = HV_EVENT_FLAGS_COUNT;
recv_int_page = event->flags;
}
if (unlikely(!recv_int_page))
return;
for_each_set_bit(relid, recv_int_page, maxbits) {
if (sync_test_and_clear_bit(relid, recv_int_page)) {
/* Special case - vmbus channel protocol msg */
if (relid != 0)
process_chn_event(relid);
}
}
}
/*
* vmbus_post_msg - Send a msg on the vmbus's message connection
*/

2
drivers/hv/hv.c
View File

@ -156,8 +156,6 @@ int hv_synic_alloc(void)
= per_cpu_ptr(hv_context.cpu_context, cpu);
memset(hv_cpu, 0, sizeof(*hv_cpu));
tasklet_init(&hv_cpu->event_dpc,
vmbus_on_event, (unsigned long) hv_cpu);
tasklet_init(&hv_cpu->msg_dpc,
vmbus_on_msg_dpc, (unsigned long) hv_cpu);

1
drivers/hv/hyperv_vmbus.h
View File

@ -206,7 +206,6 @@ struct hv_per_cpu_context {
* we will manage the tasklet that handles events messages on a per CPU
* basis.
*/
struct tasklet_struct event_dpc;
struct tasklet_struct msg_dpc;
/*

58
drivers/hv/vmbus_drv.c
View File

@ -885,6 +885,56 @@ msg_handled:
vmbus_signal_eom(msg, message_type);
}
/*
* Schedule all channels with events pending
*/
static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu)
{
unsigned long *recv_int_page;
u32 maxbits, relid;
if (vmbus_proto_version < VERSION_WIN8) {
maxbits = MAX_NUM_CHANNELS_SUPPORTED;
recv_int_page = vmbus_connection.recv_int_page;
} else {
/*
* When the host is win8 and beyond, the event page
* can be directly checked to get the id of the channel
* that has the interrupt pending.
*/
void *page_addr = hv_cpu->synic_event_page;
union hv_synic_event_flags *event
= (union hv_synic_event_flags *)page_addr +
VMBUS_MESSAGE_SINT;
maxbits = HV_EVENT_FLAGS_COUNT;
recv_int_page = event->flags;
}
if (unlikely(!recv_int_page))
return;
for_each_set_bit(relid, recv_int_page, maxbits) {
struct vmbus_channel *channel;
if (!sync_test_and_clear_bit(relid, recv_int_page))
continue;
/* Special case - vmbus channel protocol msg */
if (relid == 0)
continue;
/* Find channel based on relid */
list_for_each_entry(channel, &hv_cpu->chan_list, percpu_list) {
if (channel->offermsg.child_relid == relid) {
tasklet_schedule(&channel->callback_event);
break;
}
}
}
}
static void vmbus_isr(void)
{
struct hv_per_cpu_context *hv_cpu
@ -922,8 +972,7 @@ static void vmbus_isr(void)
}
if (handled)
tasklet_schedule(&hv_cpu->event_dpc);
vmbus_chan_sched(hv_cpu);
page_addr = hv_cpu->synic_message_page;
msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
@ -1536,12 +1585,7 @@ static void __exit vmbus_exit(void)
&hyperv_panic_block);
}
bus_unregister(&hv_bus);
for_each_online_cpu(cpu) {
struct hv_per_cpu_context *hv_cpu
= per_cpu_ptr(hv_context.cpu_context, cpu);
tasklet_kill(&hv_cpu->event_dpc);
}
cpuhp_remove_state(hyperv_cpuhp_online);
hv_synic_free();
acpi_bus_unregister_driver(&vmbus_acpi_driver);

3
include/linux/hyperv.h
View File

@ -35,7 +35,7 @@
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/mod_devicetable.h>
#include <linux/interrupt.h>
#define MAX_PAGE_BUFFER_COUNT 32
#define MAX_MULTIPAGE_BUFFER_COUNT 32 /* 128K */
@ -743,6 +743,7 @@ struct vmbus_channel {
struct vmbus_close_msg close_msg;
/* Channel callback's invoked in softirq context */
struct tasklet_struct callback_event;
void (*onchannel_callback)(void *context);
void *channel_callback_context;