[Qemu-devel] Problem with allocation of big files

[Nikita A Menkovich]

Hello,

I found a strange problem with allocationg big files on drive.

For example in guestfish I allocate large disk image
for example:

$ guestfish
><fs> allocate test.img 20G

When an image allocating, there is a big slowdown of guest OSes,
launched on host machine, and on different drives.

For Linux guests with virtio drivers, there is no so big performance
penalty, but for FreeBSD guests with ide it seems like the OS locked.

Manipulating with ionice and niceness do not affect at all.

Manipulating with cfq, deadline schedulers also do not have any results.

OS Debian Squeeze
libvirtd (libvirt) 0.9.2
QEMU emulator version 0.14.0 (Debian 0.14.0+dfsg-5.1), Copyright (c)
2003-2008 Fabrice Bellard
guestfish 1.10.3 with some local patches, backported from main tree

Does anyone have ideas how to fix it?

-- 
Nikita A Menkovich
http://libc6.org/
JID: address@hidden