From: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] [Bug 1774605] Re: PowerPC guest does not emulate L2 and L3 cache for KVM vCPUs
Date: Fri, 01 Jun 2018 08:50:27 -0000 [thread overview]
Message-ID: <152784302714.24827.17278453901114931202.malone@gac.canonical.com> (raw)
In-Reply-To: 152784273656.31479.153660947051184788.malonedeb@soybean.canonical.com
Guest xml(cpu portion):
...
<vcpu placement='static' current='16'>32</vcpu>
<resource>
<partition>/machine</partition>
</resource>
<os>
<type arch='ppc64le' machine='pseries-2.13'>hvm</type>
<kernel>/home/kvmci/linux/vmlinux</kernel>
<cmdline>root=/dev/sda2 rw console=tty0 console=ttyS0,115200 init=/sbin/init initcall_debug</cmdline>
<boot dev='hd'/>
</os>
<cpu mode='host-passthrough' check='none'>
<topology sockets='2' cores='2' threads='8'/>
</cpu>
...
Host lscpu:
# lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 80
On-line CPU(s) list: 0,8,16,24,32,40,48,56,64,72
Off-line CPU(s) list: 1-7,9-15,17-23,25-31,33-39,41-47,49-55,57-63,65-71,73-79
Thread(s) per core: 1
Core(s) per socket: 5
Socket(s): 2
NUMA node(s): 2
Model: 2.1 (pvr 004b 0201)
Model name: POWER8E (raw), altivec supported
CPU max MHz: 3690.0000
CPU min MHz: 2061.0000
L1d cache: 64K
L1i cache: 32K
L2 cache: 512K
L3 cache: 8192K
NUMA node0 CPU(s): 0,8,16,24,32
NUMA node1 CPU(s): 40,48,56,64,72
--
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https://bugs.launchpad.net/bugs/1774605
Title:
PowerPC guest does not emulate L2 and L3 cache for KVM vCPUs
Status in QEMU:
New
Bug description:
PowerPC KVM guest does not emulate L2 and L2 caches for vCPU, it would
be good to have them enabled if not any known issues/limitation
already with PowerPC.
Host Env:
kernel: 4.17.0-rc7-00045-g0512e0134582
qemu: v2.12.0-923-gc181ddaa17-dirty
#libvirtd -V
libvirtd (libvirt) 4.4.0
Guest Kernel:
# uname -a
Linux atest-guest 4.17.0-rc7-00045-g0512e0134582 #9 SMP Fri Jun 1 02:55:50 EDT 2018 ppc64le ppc64le ppc64le GNU/Linux
Guest:
# lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 16
On-line CPU(s) list: 0-15
Thread(s) per core: 8
Core(s) per socket: 2
Socket(s): 1
NUMA node(s): 1
Model: 2.1 (pvr 004b 0201)
Model name: POWER8 (architected), altivec supported
Hypervisor vendor: KVM
Virtualization type: para
L1d cache: 64K
L1i cache: 32K
NUMA node0 CPU(s): 0-15
background: x86 enabling cpu L2 cache bydefault and L3 cache on demand for kvm guest
and claims performance improvement as vcpus can be
benefited with lesser `vmexits due to guest send IPIs.` with L3 cache enabled, below was patch for same.
https://git.qemu.org/?p=qemu.git;a=commit;h=14c985cffa6cb177fc01a163d8bcf227c104718c
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1774605/+subscriptions
next prev parent reply other threads:[~2018-06-01 9:00 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-01 8:45 [Qemu-devel] [Bug 1774605] [NEW] PowerPC guest does not emulate L2 and L3 cache for KVM vCPUs Satheesh Rajendran
2018-06-01 8:50 ` Satheesh Rajendran [this message]
2018-06-01 14:51 ` [Qemu-devel] [Bug 1774605] " Satheesh Rajendran
2020-11-24 16:29 ` Thomas Huth
2021-04-22 5:53 ` Thomas Huth
2021-06-22 4:17 ` Launchpad Bug Tracker
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