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* [bug report] iommu_dma_unmap_sg() is very slow then running IO from remote numa node
@ 2021-07-09  8:38 Ming Lei
  2021-07-09 10:16 ` Russell King (Oracle)
  2021-07-09 10:26 ` Robin Murphy
  0 siblings, 2 replies; 30+ messages in thread
From: Ming Lei @ 2021-07-09  8:38 UTC (permalink / raw)
  To: linux-nvme, Will Deacon, linux-arm-kernel, iommu; +Cc: linux-kernel

Hello,

I observed that NVMe performance is very bad when running fio on one
CPU(aarch64) in remote numa node compared with the nvme pci numa node.

Please see the test result[1] 327K vs. 34.9K.

Latency trace shows that one big difference is in iommu_dma_unmap_sg(),
1111 nsecs vs 25437 nsecs.


[1] fio test & results

1) fio test result:

- run fio on local CPU
taskset -c 0 ~/git/tools/test/nvme/io_uring 10 1 /dev/nvme1n1 4k
+ fio --bs=4k --ioengine=io_uring --fixedbufs --registerfiles --hipri --iodepth=64 --iodepth_batch_submit=16 --iodepth_batch_complete_min=16 --filename=/dev/nvme1n1 --direct=1 --runtime=10 --numjobs=1 --rw=randread --name=test --group_reporting

IOPS: 327K
avg latency of iommu_dma_unmap_sg(): 1111 nsecs


- run fio on remote CPU
taskset -c 80 ~/git/tools/test/nvme/io_uring 10 1 /dev/nvme1n1 4k
+ fio --bs=4k --ioengine=io_uring --fixedbufs --registerfiles --hipri --iodepth=64 --iodepth_batch_submit=16 --iodepth_batch_complete_min=16 --filename=/dev/nvme1n1 --direct=1 --runtime=10 --numjobs=1 --rw=randread --name=test --group_reporting

IOPS: 34.9K
avg latency of iommu_dma_unmap_sg(): 25437 nsecs

2) system info
[root@ampere-mtjade-04 ~]# lscpu | grep NUMA
NUMA node(s):                    2
NUMA node0 CPU(s):               0-79
NUMA node1 CPU(s):               80-159

lspci | grep NVMe
0003:01:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM981/PM981/PM983

[root@ampere-mtjade-04 ~]# cat /sys/block/nvme1n1/device/device/numa_node
0



Thanks, 
Ming


^ permalink raw reply	[flat|nested] 30+ messages in thread

end of thread, other threads:[~2021-08-10 10:36 UTC | newest]

Thread overview: 30+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-07-09  8:38 [bug report] iommu_dma_unmap_sg() is very slow then running IO from remote numa node Ming Lei
2021-07-09 10:16 ` Russell King (Oracle)
2021-07-09 14:21   ` Ming Lei
2021-07-09 10:26 ` Robin Murphy
2021-07-09 11:04   ` John Garry
2021-07-09 12:34     ` Robin Murphy
2021-07-09 14:24   ` Ming Lei
2021-07-19 16:14     ` John Garry
2021-07-21  1:40       ` Ming Lei
2021-07-21  9:23         ` John Garry
2021-07-21  9:59           ` Ming Lei
2021-07-21 11:07             ` John Garry
2021-07-21 11:58               ` Ming Lei
2021-07-22  7:58               ` Ming Lei
2021-07-22 10:05                 ` John Garry
2021-07-22 10:19                   ` Ming Lei
2021-07-22 11:12                     ` John Garry
2021-07-22 12:53                       ` Marc Zyngier
2021-07-22 13:54                         ` John Garry
2021-07-22 15:54                       ` Ming Lei
2021-07-22 17:40                         ` Robin Murphy
2021-07-23 10:21                           ` Ming Lei
2021-07-26  7:51                             ` John Garry
2021-07-28  1:32                               ` Ming Lei
2021-07-28 10:38                                 ` John Garry
2021-07-28 15:17                                   ` Ming Lei
2021-07-28 15:39                                     ` Robin Murphy
2021-08-10  9:36                                     ` John Garry
2021-08-10 10:35                                       ` Ming Lei
2021-07-27 17:08                             ` Robin Murphy

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