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| author | K. Y. Srinivasan <kys@microsoft.com> | 2016-07-01 16:26:37 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-08-31 13:05:41 +0200 |
| commit | 3724287c0ec472815ebe5ae3790f77965c6aa557 (patch) | |
| tree | 7a7364937447691888e458e854f0ee688ecce419 /drivers/hv/channel.c | |
| parent | 8de0d7e951826d7592e0ba1da655b175c4aa0923 (diff) | |
| download | lwn-3724287c0ec472815ebe5ae3790f77965c6aa557.tar.gz lwn-3724287c0ec472815ebe5ae3790f77965c6aa557.zip | |
Drivers: hv: vmbus: Implement a mechanism to tag the channel for low latency
On Hyper-V, performance critical channels use the monitor
mechanism to signal the host when the guest posts mesages
for the host. This mechanism minimizes the hypervisor intercepts
and also makes the host more efficient in that each time the
host is woken up, it processes a batch of messages as opposed to
just one. The goal here is improve the throughput and this is at
the expense of increased latency.
Implement a mechanism to let the client driver decide if latency
is important.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hv/channel.c')
| -rw-r--r-- | drivers/hv/channel.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c index 9a49505a8e06..884cebf5f9b9 100644 --- a/drivers/hv/channel.c +++ b/drivers/hv/channel.c @@ -43,7 +43,12 @@ static void vmbus_setevent(struct vmbus_channel *channel) { struct hv_monitor_page *monitorpage; - if (channel->offermsg.monitor_allocated) { + /* + * For channels marked as in "low latency" mode + * bypass the monitor page mechanism. + */ + if ((channel->offermsg.monitor_allocated) && + (!channel->low_latency)) { /* Each u32 represents 32 channels */ sync_set_bit(channel->offermsg.child_relid & 31, (unsigned long *) vmbus_connection.send_int_page + |