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Drivers: hv: vmbus: Expose counters for interrupts and full conditions

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Counter values for per-channel interrupts and ring buffer full
conditions are useful for investigating performance.

Expose counters in sysfs for 2 types of guest to host interrupts:
1) Interrupts caused by the channel's outbound ring buffer transitioning
from empty to not empty
2) Interrupts caused by the channel's inbound ring buffer transitioning
from full to not full while a packet is waiting for enough buffer space to
become available

Expose 2 counters in sysfs for the number of times that write operations
encountered a full outbound ring buffer:
1) The total number of write operations that encountered a full
condition
2) The number of write operations that were the first to encounter a
full condition

Increment the outbound full condition counters in the
hv_ringbuffer_write() function because, for most drivers, a full
outbound ring buffer is detected in that function. Also increment the
outbound full condition counters in the set_channel_pending_send_size()
function. In the hv_sock driver, a full outbound ring buffer is detected
and set_channel_pending_send_size() is called before
hv_ringbuffer_write() is called.

I tested this patch by confirming that the sysfs files were created and
observing the counter values. The values seemed to increase by a
reasonable amount when the Hyper-v related drivers were in use.

Signed-off-by: Kimberly Brown <kimbrownkd@gmail.com>
Reviewed-by:  Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kimberly Brown 2019-02-04 02:13:09 -05:00 • committed by Sasha Levin
parent 593db80390
commit 396ae57ef1
4 changed files with 128 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

46
include/linux/hyperv.h
View file

@ -751,6 +751,19 @@ struct vmbus_channel {
u64 interrupts; /* Host to Guest interrupts */
u64 sig_events; /* Guest to Host events */
/*
* Guest to host interrupts caused by the outbound ring buffer changing
* from empty to not empty.
*/
u64 intr_out_empty;
/*
* Indicates that a full outbound ring buffer was encountered. The flag
* is set to true when a full outbound ring buffer is encountered and
* set to false when a write to the outbound ring buffer is completed.
*/
bool out_full_flag;
/* Channel callback's invoked in softirq context */
struct tasklet_struct callback_event;
void (*onchannel_callback)(void *context);
@ -903,6 +916,24 @@ struct vmbus_channel {
* vmbus_connection.work_queue and hang: see vmbus_process_offer().
*/
struct work_struct add_channel_work;
/*
* Guest to host interrupts caused by the inbound ring buffer changing
* from full to not full while a packet is waiting.
*/
u64 intr_in_full;
/*
* The total number of write operations that encountered a full
* outbound ring buffer.
*/
u64 out_full_total;
/*
* The number of write operations that were the first to encounter a
* full outbound ring buffer.
*/
u64 out_full_first;
};
static inline bool is_hvsock_channel(const struct vmbus_channel *c)
@ -936,6 +967,21 @@ static inline void *get_per_channel_state(struct vmbus_channel *c)
static inline void set_channel_pending_send_size(struct vmbus_channel *c,
u32 size)
{
unsigned long flags;
if (size) {
spin_lock_irqsave(&c->outbound.ring_lock, flags);
++c->out_full_total;
if (!c->out_full_flag) {
++c->out_full_first;
c->out_full_flag = true;
}
spin_unlock_irqrestore(&c->outbound.ring_lock, flags);
} else {
c->out_full_flag = false;
}
c->outbound.ring_buffer->pending_send_sz = size;
}