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Gabe Black a368fba7d4 Time: Add a mechanism to prevent M5 from running faster than real time.
M5 skips over any simulated time where it doesn't have any work to do. When
the simulation is active, the time skipped is short and the work done at any
point in time is relatively substantial. If the time between events is long
and/or the work to do at each event is small, it's possible for simulated time
to pass faster than real time. When running a benchmark that can be good
because it means the simulation will finish sooner in real time. When
interacting with the real world through, for instance, a serial terminal or
bridge to a real network, this can be a problem. Human or network response time
could be greatly exagerated from the perspective of the simulation and make
simulated events happen "too soon" from an external perspective.

This change adds the capability to force the simulation to run no faster than
real time. It does so by scheduling a periodic event that checks to see if
its simulated period is shorter than its real period. If it is, it stalls the
simulation until they're equal. This is called time syncing.

A future change could add pseudo instructions which turn time syncing on and
off from within the simulation. That would allow time syncing to be used for
the interactive parts of a session but then turned off when running a
benchmark using the m5 utility program inside a script. Time syncing would
probably not happen anyway while running a benchmark because there would be
plenty of work for M5 to do, but the event overhead could be avoided.
2011-01-19 11:48:00 -08:00
build_opts SCons: Support building without an ISA 2010-11-19 18:00:39 -06:00
configs Time: Add a mechanism to prevent M5 from running faster than real time. 2011-01-19 11:48:00 -08:00
ext scons: Work around for old versions of scons mistaking strings for sequences. 2010-11-09 11:03:40 -08:00
src Time: Add a mechanism to prevent M5 from running faster than real time. 2011-01-19 11:48:00 -08:00
system/arm/simple_bootloader ARM: Add code for a simple bootloader for MP boot. 2011-01-18 16:29:59 -06:00
tests ARM/O3: Add regressions for ARM w/ O3 CPU. 2011-01-18 16:30:06 -06:00
util mkblankimage: bash != sh on many systems and this script needs bash 2011-01-18 16:30:00 -06:00
.hgignore .hgignore: added src/doxygen 2010-07-27 20:00:38 -07:00
.hgtags Added tag Calvin_Submission for changeset 5de565c4b7bd 2009-11-18 11:55:42 -06:00
AUTHORS RELEASE: More changes to text 2007-11-01 21:07:49 -04:00
LICENSE Update copyright dates 2008-02-11 12:35:28 -05:00
README Update the README and RELEASE_NOTES files to prepare for beta 6. 2008-10-07 00:53:25 -04:00
RELEASE_NOTES Update the README and RELEASE_NOTES files to prepare for beta 6. 2008-10-07 00:53:25 -04:00
SConstruct time: improve time datastructure 2011-01-15 07:48:25 -08:00

This is release 2.0_beta6 of the M5 simulator.

For detailed information about building the simulator and getting
started please refer to http://www.m5sim.org.

Specific pages of interest are:
http://www.m5sim.org/wiki/index.php/Compiling_M5
http://www.m5sim.org/wiki/index.php/Running_M5

Short version:

1. If you don't have SCons version 0.96.91 or newer, get it from
http://wwww.scons.org.

2. If you don't have SWIG version 1.3.28 or newer, get it from
http://wwww.swig.org.

3. In this directory, type 'scons build/ALPHA_SE/tests/debug/quick'.  This
will build the debug version of the m5 binary (m5.debug) for the Alpha
syscall emulation target, and run the quick regression tests on it.

If you have questions, please send mail to m5-users@m5sim.org

WHAT'S INCLUDED (AND NOT)
-------------------------

The basic source release includes these subdirectories:
 - m5: 
   - src: source code of the m5 simulator
   - tests: regression tests
   - ext: less-common external packages needed to build m5

To run full-system simulations, you will need compiled console,
PALcode, and kernel binaries and one or more disk images.  These files
are collected in a separate archive, m5_system.tar.bz2.  This file
can he downloaded separately.

M5 supports Linux 2.4/2.6, FreeBSD, and the proprietary Compaq/HP
Tru64 version of Unix. We are able to distribute Linux and FreeBSD
bootdisks, but we are unable to distribute bootable disk images of
Tru64 Unix. If you have a Tru64 license and are interested in
obtaining disk images, contact us at m5-users@m5sim.org