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Commit a119845f authored by K. Y. Srinivasan's avatar K. Y. Srinivasan Committed by Greg Kroah-Hartman
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Drivers: hv: Add code to distribute channel interrupt load 



Implement a simple policy for distributing incoming interrupt load.
We classify channels as (a) performance critical and (b) not
performance critical. All non-performance critical channels will
be bound to the boot cpu. Performance critical channels will be
bound to the remaining available CPUs on a round-robin basis.

Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: default avatarHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6552ecd7

drivers/hv/channel_mgmt.c

+84 −1
Original line number Diff line number Diff line
@@ -257,6 +257,89 @@ static void vmbus_process_offer(struct work_struct *work) 
	}

}



enum {

	IDE = 0,

	SCSI,

	NIC,

	MAX_PERF_CHN,

};



/*

 * This is an array of channels (devices) that are performance critical.

 * We attempt to distribute the interrupt load for these devices across

 * all available CPUs.

 */

static const uuid_le hp_devs[] = {

	/* {32412632-86cb-44a2-9b5c-50d1417354f5} */

	/* IDE */

	{

		.b = {

			0x32, 0x26, 0x41, 0x32, 0xcb, 0x86, 0xa2, 0x44,

			0x9b, 0x5c, 0x50, 0xd1, 0x41, 0x73, 0x54, 0xf5

		}

	},

	/* {ba6163d9-04a1-4d29-b605-72e2ffb1dc7f} */

	/* Storage - SCSI */

	{

		.b  = {

			0xd9, 0x63, 0x61, 0xba, 0xa1, 0x04, 0x29, 0x4d,

			0xb6, 0x05, 0x72, 0xe2, 0xff, 0xb1, 0xdc, 0x7f

		}

	},

	/* {F8615163-DF3E-46c5-913F-F2D2F965ED0E} */

	/* Network */

	{

		.b = {

			0x63, 0x51, 0x61, 0xF8, 0x3E, 0xDF, 0xc5, 0x46,

			0x91, 0x3F, 0xF2, 0xD2, 0xF9, 0x65, 0xED, 0x0E

		}

	},



};





/*

 * We use this state to statically distribute the channel interrupt load.

 */

static u32  next_vp;



/*

 * Starting with Win8, we can statically distribute the incoming

 * channel interrupt load by binding a channel to VCPU. We

 * implement here a simple round robin scheme for distributing

 * the interrupt load.

 * We will bind channels that are not performance critical to cpu 0 and

 * performance critical channels (IDE, SCSI and Network) will be uniformly

 * distributed across all available CPUs.

 */

static u32 get_vp_index(uuid_le *type_guid)

{

	u32 cur_cpu;

	int i;

	bool perf_chn = false;

	u32 max_cpus = num_online_cpus();



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

		if (!memcmp(type_guid->b, hp_devs[i].b,

				 sizeof(uuid_le))) {

			perf_chn = true;

			break;

		}

	}

	if ((vmbus_proto_version == VERSION_WS2008) ||

	    (vmbus_proto_version == VERSION_WIN7) || (!perf_chn)) {

		/*

		 * Prior to win8, all channel interrupts are

		 * delivered on cpu 0.

		 * Also if the channel is not a performance critical

		 * channel, bind it to cpu 0.

		 */

		return 0;

	}

	cur_cpu = (++next_vp % max_cpus);

	return hv_context.vp_index[cur_cpu];

}



/*

 * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.

 *
@@ -302,7 +385,7 @@ static void vmbus_onoffer(struct vmbus_channel_message_header *hdr) 
				offer->connection_id;

	}



	newchannel->target_vp = 0;

	newchannel->target_vp = get_vp_index(&offer->offer.if_type);



	memcpy(&newchannel->offermsg, offer,

	       sizeof(struct vmbus_channel_offer_channel));