Hi All, I have a question regarding the way CPU topology is exposed to the guest.
On a 4-core Amazon AWS VM I can see the CPU topology exposed to the guest in the following manner: # lstopo Machine (7480MB) Socket L#0 + L3 L#0 (25MB) L2 L#0 (256KB) + L1d L#0 (32KB) + L1i L#0 (32KB) + Core L#0 PU L#0 (P#0) PU L#1 (P#2) L2 L#1 (256KB) + L1d L#1 (32KB) + L1i L#1 (32KB) + Core L#1 PU L#2 (P#1) PU L#3 (P#3) [...] Now trying to emulate this topology in qemu/kvm using the following command line options: -cpu Haswell,+ht -smp 4,sockets=1,cores=2,maxcpus=64,threads=2 as well as -cpu kvm64,+ht -smp 4,sockets=1,cores=2,maxcpus=64,threads=2 Shows me something like this: # lstopo Machine (1870MB) Socket L#0 L2 L#0 (4096KB) + Core L#0 L1d L#0 (32KB) + L1i L#0 (32KB) + PU L#0 (P#0) L1d L#1 (32KB) + L1i L#1 (32KB) + PU L#1 (P#1) L2 L#1 (4096KB) + Core L#1 L1d L#2 (32KB) + L1i L#2 (32KB) + PU L#2 (P#2) L1d L#3 (32KB) + L1i L#3 (32KB) + PU L#3 (P#3) [...] In other words, qemu exposes each hyperthread as if it has its own L1 data and instruction caches. Should the be a correct behavior? In all cases, what gets exposed in the guests's /proc/cpuinfo would be the same, but I wonder why the topology is different? Regards, Mohammed