A tool to simulate guest TSCs based on their host TSC, across migrations. Also provides utilities to perform time-related calculations that come up when doing work with the TSC.
This tool has two subcommands: calc and simulate.
The calc command is for
making common calculations associated with high-resolution time, such as
converting between hrtime and a TSC reading, computing a guest TSC based on
input parameters, or finding the correct a guest TSC offset. The calc
subcommands offers an implementation parameter, which implements some of the
core math functions, which require 128-bit intermediate representations, in
either Rust or assembly.
The simulate command is to simulate the value of a guest TSC over time,
including following live migration(s).
Each of the subcommands and sub-subcommands offer a variety of parameters related to making the calculations, including the integer and fractional bit size of the fixed-point number used to represent the guest/host frequency ratio.
See the help subcommands for details.
Find the current guest TSC for a guest that booted when its host TSC was 300000000000, for a current host TSC of 305000000000:
$ tsc-simulator calc guest-tsc -i 300000000000 305000000000
calculating guest TSC for parameters:
Host:
initial TSC: 300000000000 (0x45d964b800)
current TSC: 305000000000 (0x47036aaa00)
frequency: 1000000000 Hz
Guest:
initial TSC: 0 (0x0)
frequency: 1000000000 Hz
Implementation: Rust
Guest TSC: 5000000000 (0x12a05f200)
Simulate a guest running for 20 seconds, with a frequency of 1GHz, on a host with frequency 1GHz, in which the guest booted after the host was up for 1 second:
$ tsc-simulator simulate
DURATION 20 seconds
GUEST FREQUENCY 1000000000 Hz
HOST 0
START TIME 0 seconds
TSC 1000000000
FREQUENCY 1000000000 Hz
TIME GUEST_TSC HOST_TSC
=== GUEST_BOOT ==================================================================
0 0 1000000000
1 1000000000 2000000000
2 2000000000 3000000000
3 3000000000 4000000000
4 4000000000 5000000000
5 5000000000 6000000000
6 6000000000 7000000000
7 7000000000 8000000000
8 8000000000 9000000000
9 9000000000 10000000000
10 10000000000 11000000000
11 11000000000 12000000000
12 12000000000 13000000000
13 13000000000 14000000000
14 14000000000 15000000000
15 15000000000 16000000000
16 16000000000 17000000000
17 17000000000 18000000000
18 18000000000 19000000000
19 19000000000 20000000000
20 20000000000 21000000000
A guest with 0.5GHz running on a host of 2GHz:
tsc-simulator simulate -g 500000000 -f 2000000000
DURATION 20 seconds
GUEST FREQUENCY 500000000 Hz
HOST 0
START TIME 0 seconds
TSC 1000000000
FREQUENCY 2000000000 Hz
TIME GUEST_TSC HOST_TSC
=== GUEST_BOOT ==================================================================
0 0 1000000000
1 500000000 3000000000
2 1000000000 5000000000
3 1500000000 7000000000
4 2000000000 9000000000
5 2500000000 11000000000
6 3000000000 13000000000
7 3500000000 15000000000
8 4000000000 17000000000
9 4500000000 19000000000
10 5000000000 21000000000
11 5500000000 23000000000
12 6000000000 25000000000
13 6500000000 27000000000
14 7000000000 29000000000
15 7500000000 31000000000
16 8000000000 33000000000
17 8500000000 35000000000
18 9000000000 37000000000
19 9500000000 39000000000
20 10000000000 41000000000
A guest that is migrated after 10 seconds from a host with 1GHz, to a host with 2GHz:
tsc-simulator simulate --migrate "10 10000000000 2000000000"
DURATION 20 seconds
GUEST FREQUENCY 1000000000 Hz
HOST 0
START TIME 0 seconds
TSC 1000000000
FREQUENCY 1000000000 Hz
HOST 1
START TIME 10 seconds
TSC 10000000000
FREQUENCY 2000000000 Hz
TIME GUEST_TSC HOST_TSC
=== GUEST_BOOT ==================================================================
0 0 1000000000
1 1000000000 2000000000
2 2000000000 3000000000
3 3000000000 4000000000
4 4000000000 5000000000
5 5000000000 6000000000
6 6000000000 7000000000
7 7000000000 8000000000
8 8000000000 9000000000
9 9000000000 10000000000
10 10000000000 11000000000
=== MIGRATION 1 =================================================================
10 10000000000 10000000000
11 11000000000 12000000000
12 12000000000 14000000000
13 13000000000 16000000000
14 14000000000 18000000000
15 15000000000 20000000000
16 16000000000 22000000000
17 17000000000 24000000000
18 18000000000 26000000000
19 19000000000 28000000000
20 20000000000 30000000000
Multiple migrations:
simulate -d 15 --migrate "5 300000000000 2000000000" --migrate "10 100000000000 1500000000"
DURATION 15 seconds
GUEST FREQUENCY 1000000000 Hz
HOST 0
START TIME 0 seconds
TSC 1000000000
FREQUENCY 1000000000 Hz
HOST 1
START TIME 5 seconds
TSC 300000000000
FREQUENCY 2000000000 Hz
HOST 2
START TIME 10 seconds
TSC 100000000000
FREQUENCY 1500000000 Hz
TIME GUEST_TSC HOST_TSC
=== GUEST_BOOT ==================================================================
0 0 1000000000
1 1000000000 2000000000
2 2000000000 3000000000
3 3000000000 4000000000
4 4000000000 5000000000
5 5000000000 6000000000
=== MIGRATION 1 =================================================================
5 5000000000 300000000000
6 6000000000 302000000000
7 7000000000 304000000000
8 8000000000 306000000000
9 9000000000 308000000000
10 10000000000 310000000000
=== MIGRATION 2 =================================================================
10 10000000000 100000000000
11 10999999999 101500000000
12 11999999999 103000000000
13 12999999999 104500000000
14 13999999999 106000000000
15 14999999998 107500000000