https://github.com/torvalds/linux
Revision d4794f25f122aa1a8a073be51112edaa723ffff4 authored by Yazen Ghannam on 25 March 2019, 17:32:42 UTC, committed by Len Brown on 31 August 2019, 18:48:34 UTC
Turbostat currently normalizes TSC and other values by dividing by an interval. This interval is the delta between the start of one global (all counters on all CPUs) sampling and the start of another. However, this introduces a lot of jitter into the data. In order to reduce jitter, the interval calculation should be based on timestamps taken per thread and close to the start of the thread's sampling. Define a per thread time value to hold the delta between samples taken on the thread. Use the timestamp taken at the beginning of sampling to calculate the delta. Move the thread's beginning timestamp to after the CPU migration to avoid jitter due to the migration. Use the global time delta for the average time delta. Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com> Signed-off-by: Len Brown <len.brown@intel.com>
1 parent d743dae
Tip revision: d4794f25f122aa1a8a073be51112edaa723ffff4 authored by Yazen Ghannam on 25 March 2019, 17:32:42 UTC
tools/power turbostat: Make interval calculation per thread to reduce jitter
tools/power turbostat: Make interval calculation per thread to reduce jitter
Tip revision: d4794f2
Kconfig.kgdb
# SPDX-License-Identifier: GPL-2.0-only
config HAVE_ARCH_KGDB
bool
menuconfig KGDB
bool "KGDB: kernel debugger"
depends on HAVE_ARCH_KGDB
depends on DEBUG_KERNEL
help
If you say Y here, it will be possible to remotely debug the
kernel using gdb. It is recommended but not required, that
you also turn on the kernel config option
CONFIG_FRAME_POINTER to aid in producing more reliable stack
backtraces in the external debugger. Documentation of
kernel debugger is available at http://kgdb.sourceforge.net
as well as in Documentation/dev-tools/kgdb.rst. If
unsure, say N.
if KGDB
config KGDB_SERIAL_CONSOLE
tristate "KGDB: use kgdb over the serial console"
select CONSOLE_POLL
select MAGIC_SYSRQ
depends on TTY && HW_CONSOLE
default y
help
Share a serial console with kgdb. Sysrq-g must be used
to break in initially.
config KGDB_TESTS
bool "KGDB: internal test suite"
default n
help
This is a kgdb I/O module specifically designed to test
kgdb's internal functions. This kgdb I/O module is
intended to for the development of new kgdb stubs
as well as regression testing the kgdb internals.
See the drivers/misc/kgdbts.c for the details about
the tests. The most basic of this I/O module is to boot
a kernel boot arguments "kgdbwait kgdbts=V1F100"
config KGDB_TESTS_ON_BOOT
bool "KGDB: Run tests on boot"
depends on KGDB_TESTS
default n
help
Run the kgdb tests on boot up automatically without the need
to pass in a kernel parameter
config KGDB_TESTS_BOOT_STRING
string "KGDB: which internal kgdb tests to run"
depends on KGDB_TESTS_ON_BOOT
default "V1F100"
help
This is the command string to send the kgdb test suite on
boot. See the drivers/misc/kgdbts.c for detailed
information about other strings you could use beyond the
default of V1F100.
config KGDB_LOW_LEVEL_TRAP
bool "KGDB: Allow debugging with traps in notifiers"
depends on X86 || MIPS
default n
help
This will add an extra call back to kgdb for the breakpoint
exception handler which will allow kgdb to step through a
notify handler.
config KGDB_KDB
bool "KGDB_KDB: include kdb frontend for kgdb"
default n
help
KDB frontend for kernel
config KDB_DEFAULT_ENABLE
hex "KDB: Select kdb command functions to be enabled by default"
depends on KGDB_KDB
default 0x1
help
Specifiers which kdb commands are enabled by default. This may
be set to 1 or 0 to enable all commands or disable almost all
commands.
Alternatively the following bitmask applies:
0x0002 - allow arbitrary reads from memory and symbol lookup
0x0004 - allow arbitrary writes to memory
0x0008 - allow current register state to be inspected
0x0010 - allow current register state to be modified
0x0020 - allow passive inspection (backtrace, process list, lsmod)
0x0040 - allow flow control management (breakpoint, single step)
0x0080 - enable signalling of processes
0x0100 - allow machine to be rebooted
The config option merely sets the default at boot time. Both
issuing 'echo X > /sys/module/kdb/parameters/cmd_enable' or
setting with kdb.cmd_enable=X kernel command line option will
override the default settings.
config KDB_KEYBOARD
bool "KGDB_KDB: keyboard as input device"
depends on VT && KGDB_KDB
default n
help
KDB can use a PS/2 type keyboard for an input device
config KDB_CONTINUE_CATASTROPHIC
int "KDB: continue after catastrophic errors"
depends on KGDB_KDB
default "0"
help
This integer controls the behaviour of kdb when the kernel gets a
catastrophic error, i.e. for a panic or oops.
When KDB is active and a catastrophic error occurs, nothing extra
will happen until you type 'go'.
CONFIG_KDB_CONTINUE_CATASTROPHIC == 0 (default). The first time
you type 'go', you will be warned by kdb. The secend time you type
'go', KDB tries to continue. No guarantees that the
kernel is still usable in this situation.
CONFIG_KDB_CONTINUE_CATASTROPHIC == 1. KDB tries to continue.
No guarantees that the kernel is still usable in this situation.
CONFIG_KDB_CONTINUE_CATASTROPHIC == 2. KDB forces a reboot.
If you are not sure, say 0.
endif # KGDB
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