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| author | Johannes Berg | 2019-05-27 10:34:27 +0200 |
|---|---|---|
| committer | Richard Weinberger | 2019-07-02 23:27:36 +0200 |
| commit | 065038706f77a56754e8f0c2556dab7e22dfe577 (patch) | |
| tree | 00e8ea2389184678dab2abe1155988b8aa488aad /arch/um/Kconfig | |
| parent | um: Pass nsecs to os timer functions (diff) | |
| download | kernel-qcow2-linux-065038706f77a56754e8f0c2556dab7e22dfe577.tar.gz kernel-qcow2-linux-065038706f77a56754e8f0c2556dab7e22dfe577.tar.xz kernel-qcow2-linux-065038706f77a56754e8f0c2556dab7e22dfe577.zip | |
um: Support time travel mode
Sometimes it can be useful to run with "time travel" inside the
UML instance, for example for testing. For example, some tests
for the wireless subsystem and userspace are based on hwsim, a
virtual wireless adapter. Some tests can take a long time to
run because they e.g. wait for 120 seconds to elapse for some
regulatory checks. This obviously goes faster if it need not
actually wait that long, but time inside the test environment
just "bumps up" when there's nothing to do.
Add CONFIG_UML_TIME_TRAVEL_SUPPORT to enable code to support
such modes at runtime, selected on the command line:
* just "time-travel", in which time inside the UML instance
can move faster than real time, if there's nothing to do
* "time-travel=inf-cpu" in which time also moves slower and
any CPU processing takes no time at all, which allows to
implement consistent behaviour regardless of host CPU load
(or speed) or debug overhead.
An additional "time-travel-start=<seconds>" parameter is also
supported in this case to start the wall clock at this time
(in unix epoch).
With this enabled, the test mentioned above goes from a runtime
of about 140 seconds (with startup overhead and all) to being
CPU bound and finishing in 15 seconds (on my slow laptop).
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um/Kconfig')
| -rw-r--r-- | arch/um/Kconfig | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/um/Kconfig b/arch/um/Kconfig index 6b6eb938fcc1..3c3adfc486f2 100644 --- a/arch/um/Kconfig +++ b/arch/um/Kconfig @@ -184,6 +184,18 @@ config SECCOMP If unsure, say Y. +config UML_TIME_TRAVEL_SUPPORT + bool + prompt "Support time-travel mode (e.g. for test execution)" + help + Enable this option to support time travel inside the UML instance. + + After enabling this option, two modes are accessible at runtime + (selected by the kernel command line), see the kernel's command- + line help for more details. + + It is safe to say Y, but you probably don't need this. + endmenu source "arch/um/drivers/Kconfig" |