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Subject[PATCH 2/3] Drivers: hv: balloon: Execute balloon inflation in a separate context
Date
Execute the balloon inflation operation in a separate work context.
This allows us to decouple the pressure reporting activity from the
ballooning activity. Testing has shown that this decoupling makes the
guest more reponsive.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
---
drivers/hv/hv_balloon.c | 34 ++++++++++++++++++++++++----------
1 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 3787321..860e176 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -412,6 +412,11 @@ struct dm_info_msg {
* End protocol definitions.
*/

+struct balloon_state {
+ __u32 num_pages;
+ struct work_struct wrk;
+};
+
static bool hot_add;
static bool do_hot_add;
/*
@@ -429,6 +434,7 @@ static atomic_t trans_id = ATOMIC_INIT(0);

static int dm_ring_size = (5 * PAGE_SIZE);

+
/*
* Driver specific state.
*/
@@ -459,7 +465,12 @@ struct hv_dynmem_device {
unsigned int num_pages_ballooned;

/*
- * This thread handles both balloon/hot-add
+ * State to manage the ballooning (up) operation.
+ */
+ struct balloon_state balloon_wrk;
+
+ /*
+ * This thread handles hot-add
* requests from the host as well as notifying
* the host with regards to memory pressure in
* the guest.
@@ -657,9 +668,9 @@ static int alloc_balloon_pages(struct hv_dynmem_device *dm, int num_pages,



-static void balloon_up(struct hv_dynmem_device *dm, struct dm_balloon *req)
+static void balloon_up(struct work_struct *dummy)
{
- int num_pages = req->num_pages;
+ int num_pages = dm_device.balloon_wrk.num_pages;
int num_ballooned = 0;
struct dm_balloon_response *bl_resp;
int alloc_unit;
@@ -684,14 +695,14 @@ static void balloon_up(struct hv_dynmem_device *dm, struct dm_balloon *req)


num_pages -= num_ballooned;
- num_ballooned = alloc_balloon_pages(dm, num_pages,
+ num_ballooned = alloc_balloon_pages(&dm_device, num_pages,
bl_resp, alloc_unit,
&alloc_error);

if ((alloc_error) || (num_ballooned == num_pages)) {
bl_resp->more_pages = 0;
done = true;
- dm->state = DM_INITIALIZED;
+ dm_device.state = DM_INITIALIZED;
}

/*
@@ -719,7 +730,7 @@ static void balloon_up(struct hv_dynmem_device *dm, struct dm_balloon *req)
pr_info("Balloon response failed\n");

for (i = 0; i < bl_resp->range_count; i++)
- free_balloon_pages(dm,
+ free_balloon_pages(&dm_device,
&bl_resp->range_array[i]);

done = true;
@@ -775,9 +786,6 @@ static int dm_thread_func(void *dm_dev)

scan_start = jiffies;
switch (dm->state) {
- case DM_BALLOON_UP:
- balloon_up(dm, (struct dm_balloon *)recv_buffer);
- break;

case DM_HOT_ADD:
hot_add_req(dm, (struct dm_hot_add *)recv_buffer);
@@ -861,6 +869,7 @@ static void balloon_onchannelcallback(void *context)
struct dm_message *dm_msg;
struct dm_header *dm_hdr;
struct hv_dynmem_device *dm = hv_get_drvdata(dev);
+ struct dm_balloon *bal_msg;

memset(recv_buffer, 0, sizeof(recv_buffer));
vmbus_recvpacket(dev->channel, recv_buffer,
@@ -882,8 +891,12 @@ static void balloon_onchannelcallback(void *context)
break;

case DM_BALLOON_REQUEST:
+ if (dm->state == DM_BALLOON_UP)
+ pr_warn("Currently ballooning\n");
+ bal_msg = (struct dm_balloon *)recv_buffer;
dm->state = DM_BALLOON_UP;
- complete(&dm->config_event);
+ dm_device.balloon_wrk.num_pages = bal_msg->num_pages;
+ schedule_work(&dm_device.balloon_wrk.wrk);
break;

case DM_UNBALLOON_REQUEST:
@@ -937,6 +950,7 @@ static int balloon_probe(struct hv_device *dev,
dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN7;
init_completion(&dm_device.host_event);
init_completion(&dm_device.config_event);
+ INIT_WORK(&dm_device.balloon_wrk.wrk, balloon_up);

dm_device.thread =
kthread_run(dm_thread_func, &dm_device, "hv_balloon");
--
1.7.4.1


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