On 26/07/2023 10:40, Ming Lei wrote:
Take blk-mq's knowledge into account for calculating io queues.
Fix wrong queue mapping in case of kdump kernel.
On arm and ppc64, 'maxcpus=1' is passed to kdump kernel command line,
see `Documentation/admin-guide/kdump/kdump.rst`, so num_possible_cpus()
still returns all CPUs because 'maxcpus=1' just bring up one single
cpu core during booting.
blk-mq sees single queue in kdump kernel, and in driver's viewpoint
there are still multiple queues, this inconsistency causes driver to apply
wrong queue mapping for handling IO, and IO timeout is triggered.
Meantime, single queue makes much less resource utilization, and reduce
risk of kernel failure.
Cc: Xiang Chen <chenxiang66@xxxxxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
index 20e1607c6282..60d2301e7f9d 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
@@ -2550,6 +2550,9 @@ static int interrupt_preinit_v3_hw(struct hisi_hba *hisi_hba)
hisi_hba->cq_nvecs = vectors - BASE_VECTORS_V3_HW - hisi_hba->iopoll_q_cnt;
+ if (hisi_hba->cq_nvecs > scsi_max_nr_hw_queues())
+ hisi_hba->cq_nvecs = scsi_max_nr_hw_queues();
+
shost->nr_hw_queues = hisi_hba->cq_nvecs + hisi_hba->iopoll_q_cnt;
For other drivers you limit the max MSI vectors which we try to allocate
according to scsi_max_nr_hw_queues(), but here you continue to alloc the
same max vectors but then limit the driver's completion queue count. Why
not limit the max MSI vectors also here?
Thanks,
John
return devm_add_action(&pdev->dev, hisi_sas_v3_free_vectors, pdev);
