linux/arch/um
Johannes Berg 065038706f 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>
2019-07-02 23:27:36 +02:00
..
configs um: defconfig: Cleanup from old Kconfig options 2017-09-13 22:32:51 +02:00
drivers um: Remove drivers/ssl.h 2019-07-02 23:27:24 +02:00
include um: Support time travel mode 2019-07-02 23:27:36 +02:00
kernel um: Support time travel mode 2019-07-02 23:27:36 +02:00
os-Linux um: Pass nsecs to os timer functions 2019-07-02 23:27:29 +02:00
scripts License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
.gitignore um: tell git to ignore generated files 2010-03-06 11:26:28 -08:00
Kconfig um: Support time travel mode 2019-07-02 23:27:36 +02:00
Kconfig.debug um: Make GCOV depend on !KCOV 2018-12-27 22:48:19 +01:00
Makefile um: remove unused filechk_gen_header in Makefile 2018-12-22 00:35:20 +09:00
Makefile-os-Linux
Makefile-skas