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Drivers: hv: Optimize signaling in the read path

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Now that we have the infratructure for correctly determining when we
should signal the host; optimize the signaling on the read side -
signaling the guest from the host.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
K. Y. Srinivasan 2012-12-01 06:46:35 -08:00 committed by Greg Kroah-Hartman
parent 7ae3e03519
commit f878f3d59e
1 changed files with 25 additions and 3 deletions
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28
drivers/hv/connection.c
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@ -212,6 +212,9 @@ static void process_chn_event(u32 relid)
{
struct vmbus_channel *channel;
unsigned long flags;
void *arg;
bool read_state;
u32 bytes_to_read;
/*
* Find the channel based on this relid and invokes the
@ -234,10 +237,29 @@ static void process_chn_event(u32 relid)
*/
spin_lock_irqsave(&channel->inbound_lock, flags);
if (channel->onchannel_callback != NULL)
channel->onchannel_callback(channel->channel_callback_context);
else
if (channel->onchannel_callback != NULL) {
arg = channel->channel_callback_context;
read_state = channel->batched_reading;
/*
* This callback reads the messages sent by the host.
* We can optimize host to guest signaling by ensuring:
* 1. While reading the channel, we disable interrupts from
* host.
* 2. Ensure that we process all posted messages from the host
* before returning from this callback.
* 3. Once we return, enable signaling from the host. Once this
* state is set we check to see if additional packets are
* available to read. In this case we repeat the process.
*/
do {
hv_begin_read(&channel->inbound);
channel->onchannel_callback(arg);
bytes_to_read = hv_end_read(&channel->inbound);
} while (read_state && (bytes_to_read != 0));
} else {
pr_err("no channel callback for relid - %u\n", relid);
}
spin_unlock_irqrestore(&channel->inbound_lock, flags);
}