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Commit cbbb7b31 authored by Martin K. Petersen's avatar Martin K. Petersen Committed by Christoph Hellwig
Browse files

mpt2sas: Rework the MSI-X grouping code 



On systems with a non power-of-two CPU count the existing MSI-X grouping
code failed to distribute interrupts correctly. Rework the code to
handle arbitrary processor counts.

Also remove the hardcoded upper limit on the number of processors so we
can boot on large systems.

Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Acked-by: default avatarSreekanth Reddy <Sreekanth.reddy@avagotech.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 9f21316f

drivers/scsi/mpt2sas/mpt2sas_base.c

+23 −41
Original line number Diff line number Diff line
@@ -1332,53 +1332,35 @@ _base_request_irq(struct MPT2SAS_ADAPTER *ioc, u8 index, u32 vector) 
static void

_base_assign_reply_queues(struct MPT2SAS_ADAPTER *ioc)

{

	struct adapter_reply_queue *reply_q;

	int cpu_id;

	int cpu_grouping, loop, grouping, grouping_mod;

	unsigned int cpu, nr_cpus, nr_msix, index = 0;



	if (!_base_is_controller_msix_enabled(ioc))

		return;



	memset(ioc->cpu_msix_table, 0, ioc->cpu_msix_table_sz);

	/* when there are more cpus than available msix vectors,

	 * then group cpus togeather on same irq

	 */

	if (ioc->cpu_count > ioc->msix_vector_count) {

		grouping = ioc->cpu_count / ioc->msix_vector_count;

		grouping_mod = ioc->cpu_count % ioc->msix_vector_count;

		if (grouping < 2 || (grouping == 2 && !grouping_mod))

			cpu_grouping = 2;

		else if (grouping < 4 || (grouping == 4 && !grouping_mod))

			cpu_grouping = 4;

		else if (grouping < 8 || (grouping == 8 && !grouping_mod))

			cpu_grouping = 8;

		else

			cpu_grouping = 16;

	} else

		cpu_grouping = 0;



	loop = 0;

	reply_q = list_entry(ioc->reply_queue_list.next,

	     struct adapter_reply_queue, list);

	for_each_online_cpu(cpu_id) {

		if (!cpu_grouping) {

			ioc->cpu_msix_table[cpu_id] = reply_q->msix_index;

			reply_q = list_entry(reply_q->list.next,

			    struct adapter_reply_queue, list);

		} else {

			if (loop < cpu_grouping) {

				ioc->cpu_msix_table[cpu_id] =

					reply_q->msix_index;

				loop++;

			} else {

				reply_q = list_entry(reply_q->list.next,

				    struct adapter_reply_queue, list);

				ioc->cpu_msix_table[cpu_id] =

					reply_q->msix_index;

				loop = 1;

			}

		}



	nr_cpus = num_online_cpus();

	nr_msix = ioc->reply_queue_count = min(ioc->reply_queue_count,

					       ioc->facts.MaxMSIxVectors);

	if (!nr_msix)

		return;



	cpu = cpumask_first(cpu_online_mask);



	do {

		unsigned int i, group = nr_cpus / nr_msix;



		if (index < nr_cpus % nr_msix)

			group++;



		for (i = 0 ; i < group ; i++) {

			ioc->cpu_msix_table[cpu] = index;

			cpu = cpumask_next(cpu, cpu_online_mask);

		}



		index++;



	} while (cpu < nr_cpus);

}



/**