Il 19/11/2013 11:25, Peter Lieven ha scritto:
>>
>
> ~/git/qemu$ x86_64-softmmu/qemu-system-x86_64 -m 2048 -drive
> if=virtio,file=iscsi://172.21.200.45/iqn.2001-05.com.equallogic:0-8a0906-9d95c510a-344001d54795289f-2012-r2-1-7-0/0,format=raw,cache=writeback,aio=native
> -smp 2,cores=2,threads=1,sockets=1 -cpu host -monitor stdio -vnc :1
> -enable-kvm -usb -usbdevice tablet -vga cirrus -global
> virtio-blk-pci.scsi=off -serial null -parallel null -boot c
What is your host CPU's topology
> With just -smp 2 it works. However, have a look at my other email I
> think there is a bug in smp_parse, because -smp 2 yields
> cpus=2,cores=1,threads=1,sockets=1 whereas I think cores should
> be 2.
The code matching the comment in vl.c ("compute missing values, prefer
sockets over cores over threads") would be like "-smp
cpu=2,cores=1,threads=1,sockets=2", giving this code:
if (cpus == 0) {
sockets = sockets > 0 ? sockets : 1;
cores = cores > 0 ? cores : 1;
threads = threads > 0 ? threads : 1;
cpus = cores * threads * sockets;
} else if (sockets == 0) {
cores = cores > 0 ? cores : 1;
threads = threads > 0 ? threads : 1;
sockets = cpus / (cores * threads);
} else if (cores == 0) {
threads = threads > 0 ? threads : 1;
cores = cpus / (sockets * threads);
} else {
threads = cpus / (sockets * cores);
}
What you suggest is cores over threads over sockets:
if (cpus == 0) {
cores = cores > 0 ? cores : 1;
threads = threads > 0 ? threads : 1;
sockets = sockets > 0 ? sockets : 1;
cpus = cores * threads * sockets;
} else if (cores == 0) {
threads = threads > 0 ? threads : 1;
sockets = sockets > 0 ? sockets : 1;
cores = cpus / (threads * sockets);
} else if (threads == 0) {
sockets = sockets > 0 ? sockets : 1;
threads = cpus / (cores * sockets);
} else {
sockets = cpus / (cores * threads);
}
Can you test which of these two work? But I agree it's best to disable
cache-leaf forwarding.
Paolo
