Hi, When testing IO heavy work on my VM backed by Ryzen 1700 CPU, I turned to brd modules, but surprisingly, the speed is even slower than some HDD: --- $ sudo modprobe brd rd_nr=1 rd_size=1048576 $ dd if=/dev/zero of=/dev/ram0 bs=1M count=1024 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 9.9928 s, 107 MB/s --- 107MB is pretty lame... Even some HDD could be faster than this. On host, it's much better: --- $ if=/dev/zero of=/dev/ram0 bs=1M count=1024 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 0.754641 s, 1.4 GB/s --- For host hardware: CPU: Ryzen 1700 All cores @ 3.8G Mem: DDR4 2400 dual channel (8G x 2) For host software: Kernel: 4.16.3-1-ARCH Qemu: 2.11.1-2 Distribution: Archlinux VM setup is mostly default setup done by libvirt. I'm not sure if this is related to this bug: https://www.redhat.com/archives/vfio-users/2017-April/msg00019.html Thanks, Qu
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