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Andrew Cooper
2bed1bc241
Currently, a user can in principle combine the output of `xl info -n`, the
APCI tables, and some manual CPUID data to figure out which CPU numbers to
feed into `xen-hptool cpu-offline` to effectively disable SMT at runtime.
A more convenient option is to teach Xen how to perform this action.
Extend XEN_SYSCTL_cpu_hotplug with two new operations. Introduce a new
smt_up_down_helper() which wraps the cpu_{up,down}_helper() helpers with logic
which understands siblings based on their APIC_ID.
Add libxc stubs, and extend xen-hptool with smt-{enable,disable} options.
These are intended to be shorthands for a loop over cpu-{online,offline}.
To simplify the implemention, they will strictly enable/disable secondary
siblings (those with a non-zero thread id). This functionality is intended
for use in production scenarios where debugging options such as `maxcpus=` or
other manual plug/unplug configuration has not been used.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
75 lines
1.9 KiB
C
75 lines
1.9 KiB
C
/******************************************************************************
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* xc_cpu_hotplug.c - Libxc API for Xen Physical CPU hotplug Management
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*
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* Copyright (c) 2008, Shan Haitao <haitao.shan@intel.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation;
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* version 2.1 of the License.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "xc_private.h"
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int xc_cpu_online(xc_interface *xch, int cpu)
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{
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DECLARE_SYSCTL;
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int ret;
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sysctl.cmd = XEN_SYSCTL_cpu_hotplug;
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sysctl.u.cpu_hotplug.cpu = cpu;
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sysctl.u.cpu_hotplug.op = XEN_SYSCTL_CPU_HOTPLUG_ONLINE;
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ret = xc_sysctl(xch, &sysctl);
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return ret;
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}
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int xc_cpu_offline(xc_interface *xch, int cpu)
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{
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DECLARE_SYSCTL;
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int ret;
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sysctl.cmd = XEN_SYSCTL_cpu_hotplug;
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sysctl.u.cpu_hotplug.cpu = cpu;
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sysctl.u.cpu_hotplug.op = XEN_SYSCTL_CPU_HOTPLUG_OFFLINE;
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ret = xc_sysctl(xch, &sysctl);
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return ret;
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}
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int xc_smt_enable(xc_interface *xch)
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{
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DECLARE_SYSCTL;
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int ret;
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sysctl.cmd = XEN_SYSCTL_cpu_hotplug;
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sysctl.u.cpu_hotplug.cpu = 0;
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sysctl.u.cpu_hotplug.op = XEN_SYSCTL_CPU_HOTPLUG_SMT_ENABLE;
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ret = xc_sysctl(xch, &sysctl);
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return ret;
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}
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int xc_smt_disable(xc_interface *xch)
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{
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DECLARE_SYSCTL;
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int ret;
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sysctl.cmd = XEN_SYSCTL_cpu_hotplug;
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sysctl.u.cpu_hotplug.cpu = 0;
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sysctl.u.cpu_hotplug.op = XEN_SYSCTL_CPU_HOTPLUG_SMT_DISABLE;
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ret = xc_sysctl(xch, &sysctl);
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return ret;
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}
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