Negative values are special. Don't let users write them directly.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Typically when a device is created the bus core it belongs to (for example
PCI) does not know if the device supports things like latency tolerance.
This is left to the driver that binds to the device in question. However,
at that time the device has already been created and there is no way to set
its dev->power.set_latency_tolerance anymore.
So follow what has been done for other PM QoS attributes as well and allow
drivers to expose and hide latency tolerance from userspace, if the device
supports it.
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
After commit b2b49ccbdd (PM: Kconfig: Set PM_RUNTIME if PM_SLEEP is
selected) PM_RUNTIME is always set if PM is set, so quite a few
depend on CONFIG_PM or even may be dropped entirely in some cases.
Replace CONFIG_PM_RUNTIME with CONFIG_PM in the PM core code.
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The global variable "enabled" is shadowed in a number of
functions in this file, rename it to "_enabled" to avoid
that. For consistency, also rename "disabled" and move
them both into the #ifdef where they're needed.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Add a new latency tolerance device PM QoS type to be use for
specifying active state (RPM_ACTIVE) memory access (DMA) latency
tolerance requirements for devices. It may be used to prevent
hardware from choosing overly aggressive energy-saving operation
modes (causing too much latency to appear) for the whole platform.
This feature reqiures hardware support, so it only will be
available for devices having a new .set_latency_tolerance()
callback in struct dev_pm_info populated, in which case the
routine pointed to by it should implement whatever is necessary
to transfer the effective requirement value to the hardware.
Whenever the effective latency tolerance changes for the device,
its .set_latency_tolerance() callback will be executed and the
effective value will be passed to it. If that value is negative,
which means that the list of latency tolerance requirements for
the device is empty, the callback is expected to switch the
underlying hardware latency tolerance control mechanism to an
autonomous mode if available. If that value is PM_QOS_LATENCY_ANY,
in turn, and the hardware supports a special "no requirement"
setting, the callback is expected to use it. That allows software
to prevent the hardware from automatically updating the device's
latency tolerance in response to its power state changes (e.g. during
transitions from D3cold to D0), which generally may be done in the
autonomous latency tolerance control mode.
If .set_latency_tolerance() is present for the device, a new
pm_qos_latency_tolerance_us attribute will be present in the
devivce's power directory in sysfs. Then, user space can use
that attribute to specify its latency tolerance requirement for
the device, if any. Writing "any" to it means "no requirement, but
do not let the hardware control latency tolerance" and writing
"auto" to it allows the hardware to be switched to the autonomous
mode if there are no other requirements from the kernel side in the
device's list.
This changeset includes a fix from Mika Westerberg.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Rename symbols, variables, functions and structure fields related do
the resume latency device PM QoS type so that it is clear where they
belong (in particular, to avoid confusion with the latency tolerance
device PM QoS type introduced by a subsequent changeset).
Update the PM QoS documentation to better reflect its current state.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The usage of strict_strto*() is not preferred, because
strict_strto*() is obsolete. Thus, kstrto*() should be
used.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Device PM QoS sysfs attributes, if present during device removal,
are removed from within device_pm_remove(), which is too late,
since dpm_sysfs_remove() has already removed the whole attribute
group they belonged to. However, moving the removal of those
attributes to dpm_sysfs_remove() alone is not sufficient, because
in theory they still can be re-added right after being removed by it
(the device's driver is still bound to it at that point).
For this reason, move the entire desctruction of device PM QoS
constraints to dpm_sysfs_remove() and make it prevent any new
constraints from being added after it has run. Also, move the
initialization of the power.qos field in struct device to
device_pm_init_common() and drop the no longer needed
dev_pm_qos_constraints_init().
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Define two device PM QoS flags, PM_QOS_FLAG_NO_POWER_OFF
and PM_QOS_FLAG_REMOTE_WAKEUP, and introduce routines
dev_pm_qos_expose_flags() and dev_pm_qos_hide_flags() allowing the
caller to expose those two flags to user space or to hide them
from it, respectively.
After the flags have been exposed, user space will see two
additional sysfs attributes, pm_qos_no_power_off and
pm_qos_remote_wakeup, under the device's /sys/devices/.../power/
directory. Then, writing 1 to one of them will update the
PM QoS flags request owned by user space so that the corresponding
flag is requested to be set. In turn, writing 0 to one of them
will cause the corresponding flag in the user space's request to
be cleared (however, the owners of the other PM QoS flags requests
for the same device may still request the flag to be set and it
may be effectively set even if user space doesn't request that).
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Jean Pihet <j-pihet@ti.com>
Acked-by: mark gross <markgross@thegnar.org>
The subsequent patches will use struct dev_pm_qos_request for
representing both latency requests and flags requests. To make that
easier, put the node member of struct dev_pm_qos_request (under the
name "pnode") into a union called "data" that will represent the
request's value and list node depending on its type.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Jean Pihet <j-pihet@ti.com>
Reviewed-by: mark gross <markgross@thegnar.org>
The power/async device sysfs attribute is only used if both
CONFIG_PM_ADVANCED_DEBUG and CONFIG_PM_SLEEP are set, but the code
implementing it doesn't depend on CONFIG_PM_SLEEP. As a result, a
build warning appears if CONFIG_PM_ADVANCED_DEBUG is set and
CONFIG_PM_SLEEP is not set.
Fix it by adding a #ifdef CONFIG_PM_SLEEP around the code in
question.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Android uses one wakelock statistics that is only necessary for
opportunistic sleep. Namely, the prevent_suspend_time field
accumulates the total time the given wakelock has been locked
while "automatic suspend" was enabled. Add an analogous field,
prevent_sleep_time, to wakeup sources and make it behave in a similar
way.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Wakeup statistics used by Android are slightly different from what we
have in wakeup sources at the moment and there aren't any known
users of those statistics other than Android, so modify them to make
it easier for Android to switch to wakeup sources.
This removes the struct wakeup_source's hit_cout field, which is very
rough and therefore not very useful, and adds two new fields,
wakeup_count and expire_count. The first one tracks how many times
the wakeup source is activated with events_check_enabled set (which
roughly corresponds to the situations when a system power transition
to a sleep state is in progress and would be aborted by this wakeup
source if it were the only active one at that time) and the second
one is the number of times the wakeup source has been activated with
a timeout that expired.
Additionally, the last_time field is now updated when the wakeup
source is deactivated too (previously it was only updated during
the wakeup source's activation), which seems to be what Android does
with the analogous counter for wakelocks.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A runtime suspend of a device (e.g. an MMC controller) belonging to
a power domain or, in a more complicated scenario, a runtime suspend
of another device in the same power domain, may cause power to be
removed from the entire domain. In that case, the amount of time
necessary to runtime-resume the given device (e.g. the MMC
controller) is often substantially greater than the time needed to
run its driver's runtime resume callback. That may hurt performance
in some situations, because user data may need to wait for the
device to become operational, so we should make it possible to
prevent that from happening.
For this reason, introduce a new sysfs attribute for devices,
power/pm_qos_resume_latency_us, allowing user space to specify the
upper bound of the time necessary to bring the (runtime-suspended)
device up after the resume of it has been requested. However, make
that attribute appear only for the devices whose drivers declare
support for it by calling the (new) dev_pm_qos_expose_latency_limit()
helper function with the appropriate initial value of the attribute.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Most of these files were implicitly getting EXPORT_SYMBOL via
device.h which was including module.h, but that path will be broken
soon.
[ with input from Stephen Rothwell <sfr@canb.auug.org.au> ]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: Arun Sharma <asharma@fb.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch (as1475) adds device_lock() and device_unlock() calls to
the store methods for the power/control and power/autosuspend_delay_ms
sysfs attribute files. We don't want badly timed writes to these
files to cause runtime_resume callbacks to occur while a driver is
being probed for a device.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
The "wakeup" device sysfs file is only created if CONFIG_PM_SLEEP
is set, so put it under CONFIG_PM_SLEEP and make a build warning
related to it go away.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Currently, wakeup sysfs attributes are created for all devices,
regardless of whether or not they are wakeup-capable. This is
excessive and complicates wakeup device identification from user
space (i.e. to identify wakeup-capable devices user space has to read
/sys/devices/.../power/wakeup for all devices and see if they are not
empty).
Fix this issue by avoiding to create wakeup sysfs files for devices
that cannot wake up the system from sleep states (i.e. whose
power.can_wakeup flags are unset during registration) and modify
device_set_wakeup_capable() so that it adds (or removes) the relevant
sysfs attributes if a device's wakeup capability status is changed.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
This patch (as1427) implements the "autosuspend" facility for runtime
PM. A few new fields are added to the dev_pm_info structure and
several new PM helper functions are defined, for telling the PM core
whether or not a device uses autosuspend, for setting the autosuspend
delay, and for marking periods of device activity.
Drivers that do not want to use autosuspend can continue using the
same helper functions as before; their behavior will not change. In
addition, drivers supporting autosuspend can also call the old helper
functions to get the old behavior.
The details are all explained in Documentation/power/runtime_pm.txt
and Documentation/ABI/testing/sysfs-devices-power.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Some devices, such as USB interfaces, cannot be power-managed
independently of their parents, i.e., they cannot be put in low power
while the parent remains at full power. This patch (as1425) creates a
new "no_callbacks" flag, which tells the PM core not to invoke the
runtime-PM callback routines for the such devices but instead to
assume that the callbacks always succeed. In addition, the
non-debugging runtime-PM sysfs attributes for the devices are removed,
since they are pretty much meaningless.
The advantage of this scheme comes not so much from avoiding the
callbacks themselves, but rather from the fact that without the need
for a process context in which to run the callbacks, more work can be
done in interrupt context.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Introduce struct wakeup_source for representing system wakeup sources
within the kernel and for collecting statistics related to them.
Make the recently introduced helper functions pm_wakeup_event(),
pm_stay_awake() and pm_relax() use struct wakeup_source objects
internally, so that wakeup statistics associated with wakeup devices
can be collected and reported in a consistent way (the definition of
pm_relax() is changed, which is harmless, because this function is
not called directly by anyone yet). Introduce new wakeup-related
sysfs device attributes in /sys/devices/.../power for reporting the
device wakeup statistics.
Change the global wakeup events counters event_count and
events_in_progress into atomic variables, so that it is not necessary
to acquire a global spinlock in pm_wakeup_event(), pm_stay_awake()
and pm_relax(), which should allow us to avoid lock contention in
these functions on SMP systems with many wakeup devices.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
In order for PowerTOP to be able to report how well the new runtime PM is
working for the various drivers, the kernel needs to export some basic
statistics in sysfs.
This patch adds two sysfs files in the runtime PM domain that expose the
total time a device has been active, and the time a device has been
suspended.
With this PowerTOP can compute the activity percentage
Active %age = 100 * (delta active) / (delta active + delta suspended)
and present the information to the user.
I've written the PowerTOP code (slated for version 1.12) already, and the
output looks like this:
Runtime Device Power Management statistics
Active Device name
10.0% 06:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller
[version 2: fix stat update bugs noticed by Alan Stern]
[version 3: rebase to -next and move the sysfs declaration]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
This patch (as1404b) makes the runtime_status sysfs attribute available
even in the absence of CONFIG_PM_ADVANCED_DEBUG, and it changes the
routine to display "unsupported" when runtime PM is disabled for a
device. Although not strictly 100% accurate, this will almost always
be correct.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
One of the arguments during the suspend blockers discussion was that
the mainline kernel didn't contain any mechanisms making it possible
to avoid races between wakeup and system suspend.
Generally, there are two problems in that area. First, if a wakeup
event occurs exactly when /sys/power/state is being written to, it
may be delivered to user space right before the freezer kicks in, so
the user space consumer of the event may not be able to process it
before the system is suspended. Second, if a wakeup event occurs
after user space has been frozen, it is not generally guaranteed that
the ongoing transition of the system into a sleep state will be
aborted.
To address these issues introduce a new global sysfs attribute,
/sys/power/wakeup_count, associated with a running counter of wakeup
events and three helper functions, pm_stay_awake(), pm_relax(), and
pm_wakeup_event(), that may be used by kernel subsystems to control
the behavior of this attribute and to request the PM core to abort
system transitions into a sleep state already in progress.
The /sys/power/wakeup_count file may be read from or written to by
user space. Reads will always succeed (unless interrupted by a
signal) and return the current value of the wakeup events counter.
Writes, however, will only succeed if the written number is equal to
the current value of the wakeup events counter. If a write is
successful, it will cause the kernel to save the current value of the
wakeup events counter and to abort the subsequent system transition
into a sleep state if any wakeup events are reported after the write
has returned.
[The assumption is that before writing to /sys/power/state user space
will first read from /sys/power/wakeup_count. Next, user space
consumers of wakeup events will have a chance to acknowledge or
veto the upcoming system transition to a sleep state. Finally, if
the transition is allowed to proceed, /sys/power/wakeup_count will
be written to and if that succeeds, /sys/power/state will be written
to as well. Still, if any wakeup events are reported to the PM core
by kernel subsystems after that point, the transition will be
aborted.]
Additionally, put a wakeup events counter into struct dev_pm_info and
make these per-device wakeup event counters available via sysfs,
so that it's possible to check the activity of various wakeup event
sources within the kernel.
To illustrate how subsystems can use pm_wakeup_event(), make the
low-level PCI runtime PM wakeup-handling code use it.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: markgross <markgross@thegnar.org>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Add a few sysfs files relating to runtime power management for
advanced debug purposes:
runtime_enabled: is runtime PM enabled for this device? States
are "enabled", "disabled", "forbidden" or a combination
of the latter two.
runtime_status: what state is the device in currently? E.g., it
reports "suspended" for runtime-suspended devices, and
"active" for active devices. NOTE: if runtime_enabled
returns "disabled", the value of this file may not
reflect its physical state.
runtime_usage: the runtime PM usage count of a device
runtime_active_kids: the runtime PM children usage count of a device, or
0 if the ignore_children flag is set.
Also, CONFIG_PM_SLEEP_ADVANCED_DEBUG is not defined in any Kconfig
file, so replace it with CONFIG_PM_ADVANCED_DEBUG.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Add configuration switch CONFIG_PM_ADVANCED_DEBUG for compiling in
extra PM debugging/testing code allowing one to access some
PM-related attributes of devices from the user space via sysfs.
If CONFIG_PM_ADVANCED_DEBUG is set, add sysfs attribute power/async
for every device allowing the user space to access the device's
power.async_suspend flag and modify it, if desired.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Add new device sysfs attribute, power/control, allowing the user
space to block the run-time power management of the devices. If this
attribute is set to "on", the driver of the device won't be able to power
manage it at run time (without breaking the rules) and the device will
always be in the full power state (except when the entire system goes
into a sleep state).
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
* Introduce function acpi_pm_device_sleep_wake() for enabling and
disabling the system wake-up capability of devices that are power
manageable by ACPI.
* Introduce function acpi_bus_can_wakeup() allowing other (dependent)
subsystems to check if ACPI is able to enable the system wake-up
capability of given device.
* Introduce callback .sleep_wake() in struct pci_platform_pm_ops and
for the ACPI PCI 'driver' make it use acpi_pm_device_sleep_wake().
* Introduce callback .can_wakeup() in struct pci_platform_pm_ops and
for the ACPI 'driver' make it use acpi_bus_can_wakeup().
* Move the PME# handlig code out of pci_enable_wake() and split it
into two functions, pci_pme_capable() and pci_pme_active(),
allowing the caller to check if given device is capable of
generating PME# from given power state and to enable/disable the
device's PME# functionality, respectively.
* Modify pci_enable_wake() to use the new ACPI callbacks and the new
PME#-related functions.
* Drop the generic .platform_enable_wakeup() callback that is not
used any more.
* Introduce device_set_wakeup_capable() that will set the
power.can_wakeup flag of given device.
* Rework PCI device PM initialization so that, if given device is
capable of generating wake-up events, either natively through the
PME# mechanism, or with the help of the platform, its
power.can_wakeup flag is set and its power.should_wakeup flag is
unset as appropriate.
* Make ACPI set the power.can_wakeup flag for devices found to be
wake-up capable by it.
* Make the ACPI wake-up code enable/disable GPEs for devices that
have the wakeup.flags.prepared flag set (which means that their
wake-up power has been enabled).
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
The various wakeup flags and their accessor macros in struct
dev_pm_info should be available whenever CONFIG_PM is enabled, not
just when CONFIG_PM_SLEEP is on. Otherwise remote wakeup won't always
be configurable for runtime power management. This patch (as1056b)
fixes the oversight.
David Brownell adds:
More accurately, fixes the "regression" ... as noted sometime
last summer, after 296699de6b
introduced CONFIG_SUSPEND. But that didn't make the regression
list for that kernel, ergo the delay in fixing it.
[rjw: rebased]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Add a new PM_SYSFS_DEPRECATED config option to control whether or
not the /sys/devices/.../power/state files are provided. This will
make it easier to get rid of that mechanism when the time comes,
and to verify that userspace tools work right without it.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Updates to match current code:
- Make writes to the /sys/devices/.../power/state files fail cleanly
if the device requires the irqs-off call variants.
- Fix comments describing the /sys/devices/.../power/state file writes
to match the code; the last several releases have invalidated the
previous text.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Fix more include file problems that surfaced since I submitted the previous
fix-missing-includes.patch. This should now allow not to include sched.h
from module.h, which is done by a followup patch.
Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This is a refresh of an earlier patch to add "wakeup" support to the
PM core model. This provides per-device bus-neutral control of the
use of wakeup events.
* "struct device_pm_info" has two bits that are initialized as
part of setting up the enclosing struct device:
- "can_wakeup", reflecting hardware capabilities
- "may_wakeup", the policy setting (when CONFIG_PM)
* There's a writeable sysfs "wakeup" file, with one of two values:
- "enabled", when the policy is to allow wakeup
- "disabled", when the policy is not to allow it
- "" if the device can't currently issue wakeups
By default, wakeup is enabled on all devices that support it. If its
driver doesn't support it ... treat it as a bug. :)
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This adds type-checking to pm_message_t, so that people can't confuse it
with int or u32. It also allows us to fix "disk yoyo" during suspend (disk
spinning down/up/down).
[We've tried that before; since that cpufreq problems were fixed and I've
tried make allyes config and fixed resulting damage.]
Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Alexander Nyberg <alexn@telia.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Andrew Lutomirski