[Qemu-devel] Hight Processor time of Socket communciation

[Jiahuan Zhang]

Dear QEMU developers,
I am measuring the processor time for guest-host communication via socket.
The guest app is to write a 5M image to a serial device.
The serial deivce is redirected to the socket in the command line.
The host app is to receive the data via socket until the peer closes the
connection.
Please find in the attachment the Processor time graph generated by Windows
Performance Monitor.

The graph shows the processor time is almost 100% while communicating.
Surprising me! My expectation is 1%.

I wonder if this is the right performance for QEMU socket communciation? Or
this high processor time is caused by the serial device? If so, any
optimization I can do?

Here is the QEMU command-line i used.
$ qemu/build/arm-softmmu/qemu-system-arm.exe -M vexpress-a9 -kernel
zImage_vexpress_4-10 -dtb vexpress-v2p-ca9.dtb -initrd rootfs.img.gz
-append "console=ttyAMA0 root=/dev/ram rdinit=linuxrc" -chardev
socket,host=localhost,port=27015,server,nowait,id=char1 -serial
telnet:localhost:5555,server,nowait -serial stdio -serial stdio -serial
chardev:char1 -monitor telnet:localhost:4444,server,nowait -sd test.img
-nographic

Please correct me if something is wrong.

Best rergards,

Huan

socket_guest.png
Description: PNG image