Hi All,

SPDK perf test queue size more than 8187 fails.

Test procedure:
1. Increase the number of huge pages to 4096 - that means total huge page memory reserved is 4096 * 2048KB. that means 8GB
$echo 4096 >/proc/sys/vm/nr_hugepages
2. Run the perf test with queue size as 8188 (or above) and DPDK memory allocation to be around 6GB.
/usr/share/spdk/examples/nvme/perf -r 'trtype:PCIe traddr:0001:01:00.0' -q 8188 -s 2048 -w read -d 6144 -t 30 -c 0x1
3. Observer the test fails at "spdk_nvme_ns_cmd_read" for one request. (it seems 8187 requests succeeds, any number above that fails
4. Observe the aplication also hangs
5. run the same test with queue size as 8187 and observe the test passes
/usr/share/spdk/examples/nvme/perf -r 'trtype:PCIe traddr:0001:01:00.0' -q 8187 -s 2048 -w read -d 6144 -t 30 -c 0x1

THE COMMAND OUTPUT IS:
root@bcm958742t:~# /usr/share/spdk/examples/nvme/perf -r 'trtype:PCIe traddr:0001:01:00.0' -q 8188 -s 2048 -w read -d 6144 -t 30 -c 0x1
Starting DPDK 16.11.1 initialization...
[ DPDK EAL parameters: perf -c 1 -m 6144 --file-prefix=spdk_pid10557 ]
EAL: Detected 8 lcore(s)
EAL: Probing VFIO support...
EAL: VFIO support initialized
EAL: cannot open /proc/self/numa_maps, consider that all memory is in socket_id 0
Initializing NVMe Controllers
EAL: PCI device 0001:01:00.0 on NUMA socket 0
EAL: probe driver: 8086:953 spdk_nvme
EAL: using IOMMU type 1 (Type 1)
[151516.159960] vfio-pci 0001:01:00.0: enabling device (0400 -> 0402)
[151516.272405] vfio_ecap_init: 0001:01:00.0 hiding ecap 0x19@0x2a0
Attaching to NVMe Controller at 0001:01:00.0 [8086:0953]
Attached to NVMe Controller at 0001:01:00.0 [8086:0953]
Associating INTEL SSDPEDMW400G4 (CVCQ6433008P400AGN ) with lcore 0
Initialization complete. Launching workers.
Starting thread on core 0
starting I/O failed

Regards,

Oza.