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Commit ce59fec8 authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Greg Kroah-Hartman
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Drivers: hv: vmbus: distribute subchannels among all vcpus 



Primary channels are distributed evenly across all vcpus we have. When the host
asks us to create subchannels it usually makes us num_cpus-1 offers and we are
supposed to distribute the work evenly among the channel itself and all its
subchannels. Make sure they are all assigned to different vcpus.

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f38e7dd7

drivers/hv/channel_mgmt.c

+28 −1
Original line number Diff line number Diff line
@@ -387,6 +387,8 @@ static void init_vp_index(struct vmbus_channel *channel, const uuid_le *type_gui 
	int i;

	bool perf_chn = false;

	u32 max_cpus = num_online_cpus();

	struct vmbus_channel *primary = channel->primary_channel, *prev;

	unsigned long flags;



	for (i = IDE; i < MAX_PERF_CHN; i++) {

		if (!memcmp(type_guid->b, hp_devs[i].guid,
@@ -407,7 +409,32 @@ static void init_vp_index(struct vmbus_channel *channel, const uuid_le *type_gui 
		channel->target_vp = 0;

		return;

	}



	/*

	 * Primary channels are distributed evenly across all vcpus we have.

	 * When the host asks us to create subchannels it usually makes us

	 * num_cpus-1 offers and we are supposed to distribute the work evenly

	 * among the channel itself and all its subchannels. Make sure they are

	 * all assigned to different vcpus.

	 */

	if (!primary)

		cur_cpu = (++next_vp % max_cpus);

	else {

		/*

		 * Let's assign the first subchannel of a channel to the

		 * primary->target_cpu+1 and all the subsequent channels to

		 * the prev->target_cpu+1.

		 */

		spin_lock_irqsave(&primary->lock, flags);

		if (primary->num_sc == 1)

			cur_cpu = (primary->target_cpu + 1) % max_cpus;

		else {

			prev = list_prev_entry(channel, sc_list);

			cur_cpu = (prev->target_cpu + 1) % max_cpus;

		}

		spin_unlock_irqrestore(&primary->lock, flags);

	}



	channel->target_cpu = cur_cpu;

	channel->target_vp = hv_context.vp_index[cur_cpu];

}