Lines Matching refs:on
9 Proper selection of tsc_mode depends on an understanding not only of
11 ever run on this guest OS. This is because tsc_mode applies
12 equally to both the OS and ALL apps that are running on this
118 To understand tsc_mode completely, some background on TSC is required:
120 The x86 "timestamp counter", or TSC, is a 64-bit register on each
122 every processor cycle, but on recent processors, it increases
134 between processors. Thus if an application were to read the TSC on
140 dependency on TSC and replaced their timestamp needs with OS-specific
148 in all power states, even on multi-socket machines, and provide a
152 tasks when running on these recent machines.
155 invariant as "TSC-safe" and any hardware on which TSC is not (or
163 We will refer to apps that might break if running on a TSC-unsafe
172 may be "safe" on one machine, it is essentially impossible to precisely
182 TSC register. The rdtscp instruction is a variant of rdtsc on recent
204 hardware on which the virtual machine is launched. If it is
219 on top of Xen), and utilizes a variation of the rdtsc instruction
220 called rdtscp that is available on most recent generation processors.
223 When a pvrdtscp-modified app is running on a processor that is both TSC-safe
227 running on a TSC-unsafe processor or a processor that doesn't support
233 highest performance is only obtained on TSC-safe machines that
234 support the rdtscp instruction; when running on older machines,
235 rdtscp is emulated and thus slower. For more information on PVRDTSCP,
243 or a tsc_mode==3 domain when it is running on TSC-unsafe hardware.
256 in a cpuid bit on the most recent x86 processors. If set, TSC invariance
259 was properly initialized to zero on all processors at boot-time
275 on a physical machine with "TSC Invariant", Linux 2.6.30+ will safely
286 decisions based on that bit. This is still an unsolved problem, though
295 page based on the current virtual CPU (vcpu) in order to properly adapt to
307 to the same value on all vcpus running any domain with tsc_mode==3;
310 and, when the domain is running on a physical machine that either
313 TSC_AUX to zero on all processors.
323 determining if it is currently running on Xen, next whether
344 (tsc_mode=3) is created on a host that provides constant TSC, its