[Expired for QEMU because there has been no activity for 60 days.]
** Changed in: qemu
Status: Incomplete => Expired
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https://bugs.launchpad.net/bugs/1253563
Title:
bad performance with rng-egd backend
Status in QEMU:
Expired
Bug description:
1. create listen socket
# cat /dev/random | nc -l localhost 1024
2. start vm with rng-egd backend
./x86_64-softmmu/qemu-system-x86_64 --enable-kvm -mon
chardev=qmp,mode=control,pretty=on -chardev
socket,id=qmp,host=localhost,port=1234,server,nowait -m 2000 -device
virtio-net-pci,netdev=h1,id=vnet0 -netdev tap,id=h1 -vnc :0 -drive
file=/images/RHEL-64-virtio.qcow2 \
-chardev socket,host=localhost,port=1024,id=chr0 \
-object rng-egd,chardev=chr0,id=rng0 \
-device virtio-rng-pci,rng=rng0,max-bytes=1024000,period=1000
(guest) # dd if=/dev/hwrng of=/dev/null
note: cancelling dd process by Ctrl+c, it will return the read speed.
Problem: the speed is around 1k/s
===================
If I use rng-random backend (filename=/dev/random), the speed is about
350k/s).
It seems that when the request entry is added to the list, we don't read the
data from queue list immediately.
The chr_read() is delayed, the virtio_notify() is delayed. the next request
will also be delayed. It effects the speed.
I tried to change rng_egd_chr_can_read() always returns 1, the speed
is improved to (about 400k/s)
Problem: we can't poll the content in time currently
Any thoughts?
Thanks, Amos
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