A dataspace capability request to a ROM service may invalidate any
previously issued dataspace. Therefor no requests should be made while a
session dataspace is mapped. Reducing calls to the session also improves
performance where servicing a ROM request has a significant cost.
Fix#2418
The 'Stack_area_ram_session' is now a 'Stack_area_ram_allocator', which
simplifies the code and remove a dependency from the 'Ram_session'
interface, which we want to remove after all.
Issue #2407
By supplying a statically allocated initial block to the slab allocator
for signal contexts, we become able to construct a 'Signal_broker' (the
back end for the PD's signalling API) without any dynamic memory
allocation. This is a precondition for using the PD as meta-data
allocator for its contained signal broker (meta data allocations must
not happen before the PD construction is complete).
Issue #2407
By separating the session-interface concerns from the mechanics of the
dataspace creation, the code becomes simpler to follow, and the RAM
session can be more easily merged with the PD session in a subsequent
step.
Issue #2407
This patch allows core's 'Signal_transmitter' implementation to sidestep
the 'Env::Pd' interface and thereby adhere to a stricter layering within
core. The 'Signal_transmitter' now uses - on kernels that depend on it -
a dedicated (and fairly freestanding) RPC proxy mechanism for signal
deliver, instead of channeling signals through the 'Pd_session::submit'
RPC function.
Previously, the Genode::Timer::curr_time always used the
Timer_session::elapsed_ms RPC as back end. Now, Genode::Timer reads
this remote time only in a periodic fashion independently from the calls
to Genode::Timer::curr_time. If now one calls Genode::Timer::curr_time,
the function takes the last read remote time value and adapts it using
the timestamp difference since the remote-time read. The conversion
factor from timestamps to time is estimated on every remote-time read
using the last read remote-time value and the timestamp difference since
the last remote time read.
This commit also re-works the timeout test. The test now has two stages.
In the first stage, it tests fast polling of the
Genode::Timer::curr_time. This stage checks the error between locally
interpolated and timer-driver time as well as wether the locally
interpolated time is monotone and sufficiently homogeneous. In the
second stage several periodic and one-shot timeouts are scheduled at
once. This stage checks if the timeouts trigger sufficiently precise.
This commit adds the new Kernel::time syscall to base-hw. The syscall is
solely used by the Genode::Timer on base-hw as substitute for the
timestamp. This is because on ARM, the timestamp function uses the ARM
performance counter that stops counting when the WFI (wait for
interrupt) instruction is active. This instruction, however is used by
the base-hw idle contexts that get active when no user thread needs to
be scheduled. Thus, the ARM performance counter is not a good choice for
time interpolation and we use the kernel internal time instead.
With this commit, the timeout library becomes a basic library. That means
that it is linked against the LDSO which then provides it to the program it
serves. Furthermore, you can't use the timeout library anymore without the
LDSO because through the kernel-dependent LDSO make-files we can achieve a
kernel-dependent timeout implementation.
This commit introduces a structured Duration type that shall successively
replace the use of Microseconds, Milliseconds, and integer types for duration
values.
Open issues:
* The timeout test fails on Raspberry PI because of precision errors in the
first stage. However, this does not render the framework unusable in general
on the RPI but merely is an issue when speaking of microseconds precision.
* If we run on ARM with another Kernel than HW the timestamp speed may
continuously vary from almost 0 up to CPU speed. The Timer, however,
only uses interpolation if the timestamp speed remained stable (12.5%
tolerance) for at least 3 observation periods. Currently, one period is
100ms, so its 300ms. As long as this is not the case,
Timer_session::elapsed_ms is called instead.
Anyway, it might happen that the CPU load was stable for some time so
interpolation becomes active and now the timestamp speed drops. In the
worst case, we would now have 100ms of slowed down time. The bad thing
about it would be, that this also affects the timeout of the period.
Thus, it might "freeze" the local time for more than 100ms.
On the other hand, if the timestamp speed suddenly raises after some
stable time, interpolated time can get too fast. This would shorten the
period but nonetheless may result in drifting away into the far future.
Now we would have the problem that we can't deliver the real time
anymore until it has caught up because the output of Timer::curr_time
shall be monotone. So, effectively local time might "freeze" again for
more than 100ms.
It would be a solution to not use the Trace::timestamp on ARM w/o HW but
a function whose return value causes the Timer to never use
interpolation because of its stability policy.
Fixes#2400
This patch make sure that a once managed parent RPC object will always be
dissolved if an exception during the remaining child construction
occurs. The original version would miss the dissolve call if one of the
subsequent members throws an exception at construction time.
This patch eases the debugging of situations where a session-object
constructor wrongly throws an exception type not specified in the
'Local_service::Factory' interface.
This patch reduces the number of exception types by facilitating
globally defined exceptions for common usage patterns shared by most
services. In particular, RPC functions that demand a session-resource
upgrade not longer reflect this condition via a session-specific
exception but via the 'Out_of_ram' or 'Out_of_caps' types.
Furthermore, the 'Parent::Service_denied', 'Parent::Unavailable',
'Root::Invalid_args', 'Root::Unavailable', 'Service::Invalid_args',
'Service::Unavailable', and 'Local_service::Factory::Denied' types have
been replaced by the single 'Service_denied' exception type defined in
'session/session.h'.
This consolidation eases the error handling (there are fewer exceptions
to handle), alleviates the need to convert exceptions along the
session-creation call chain, and avoids possible aliasing problems
(catching the wrong type with the same name but living in a different
scope).
This patch mirrors the accounting and trading scheme that Genode employs
for physical memory to the accounting of capability allocations.
Capability quotas must now be explicitly assigned to subsystems by
specifying a 'caps=<amount>' attribute to init's start nodes.
Analogously to RAM quotas, cap quotas can be traded between clients and
servers as part of the session protocol. The capability budget of each
component is maintained by the component's corresponding PD session at
core.
At the current stage, the accounting is applied to RPC capabilities,
signal-context capabilities, and dataspace capabilities. Capabilities
that are dynamically allocated via core's CPU and TRACE service are not
yet covered. Also, the capabilities allocated by resource multiplexers
outside of core (like nitpicker) must be accounted by the respective
servers, which is not covered yet.
If a component runs out of capabilities, core's PD service prints a
warning to the log. To observe the consumption of capabilities per
component in detail, the PD service is equipped with a diagnostic
mode, which can be enabled via the 'diag' attribute in the target
node of init's routing rules. E.g., the following route enables the
diagnostic mode for the PD session of the "timer" component:
<default-route>
<service name="PD" unscoped_label="timer">
<parent diag="yes"/>
</service>
...
</default-route>
For subsystems based on a sub-init instance, init can be configured
to report the capability-quota information of its subsystems by
adding the attribute 'child_caps="yes"' to init's '<report>'
config node. Init's own capability quota can be reported by adding
the attribute 'init_caps="yes"'.
Fixes#2398
This patch reworks the implementation of core's RAM service to make use
of the 'Session_object' and to remove the distinction between the
"metadata" quota and the managed RAM quota. With the new implementation,
the session implicitly allocates its metadata from its own account. So
there is not need to handle 'Out_of_metadata' and 'Quota_exceeded' via
different exceptions. Instead, the new version solely uses the
'Out_of_ram' exception.
Furthermore, the 'Allocator::Out_of_memory' exception has become an alias
for 'Out_of_ram', which simplifies the error handling.
Issue #2398
The 'Session_object' unifies several aspects of server-component
implementations:
* It keeps track of session quotas and is equipped with standardized
interfaces (Quota_guard) to upgrade (and in the future potentially
downgrade) session quotas in a uniform way.
* It follows the pattern of modern RPC objects / signal handlers that
manage/dissolve themselves at the entrypoint given as constructor
argument. Thereby, the relationship with its entrypoint is always
coupled with the lifetime of the session-component object.
* It stores the session label, which was previously done manually by
most but not all server-component implementations.
* It stores the session 'diag' flag.
* It is equipped with output methods 'diag', 'error', and 'warning'.
All messages printed from the context of a session component is
automatically prefixed with the session type and client label.
Messages passed via 'diag' are only printed if the 'diag' flag of
the session is set.
Issue #2398
The 'diag' flag can be defined by a target node of a route in init's
configuration. It is propagated as session argument to the server, which
may evaluate the flag to enable diagnostic output for the corresponding
session.
Issue #2398
This patch makes use of the new 'Quota_transfer::Account' by the service
types in base/service.h and uses 'Quota_transfer' objects in
base/child.cc and init/server.cc.
Furthermore, it decouples the notion of an 'Async_service' from
'Child_service'. Init's 'Routed_service' is no longer a 'Child_service'
but is based on the new 'Async_service' instead.
With this patch in place, quota transfers do no longer implicitly use
'Ram_session_client' objects. So transfers can in principle originate
from component-local 'Ram_session_component' objects, e.g., as used by
noux. Therefore, this patch removes a strumbling block for turning noux
into a single threaded component in the future.
Issue #2398
The 'Quota_transfer' helper facilitated the implementation of quota
transfers between components in a transactional manner. It is designated
for framework-internal use (replacing the 'Transfer' class in child.h).
However, since it is also useful for init, we make it publicly
available.
The 'Quota_transfer::Account' class serves as an interface representing
the donor or receiver of quotas (parent, service, client).
Issue #2398
This patch replaces the 'Parent::Quota_exceeded',
'Service::Quota_exceeded', and 'Root::Quota_exceeded' exceptions
by the single 'Insufficient_ram_quota' exception type.
Furthermore, the 'Parent' interface distinguished now between
'Out_of_ram' (the child's RAM is exhausted) from
'Insufficient_ram_quota' (the child's RAM donation does not suffice to
establish the session).
This eliminates ambiguities and removes the need to convert exception
types along the path of the session creation.
Issue #2398
This patch adds sanity checks to the RPC entrypoint that detect attempts
to manage or dissolve the same RPC object twice. This is not always a
bug. I.e., if RPC objects are implemented in the modern way where the
object manages/dissolves itself. As the generic framework code (in
particular root/component.h) cannot rely on this pattern, it has to
call manage/dissolve for session objects anyway. For modern session
objects, this double attempt would result in a serious error (double
insertion into the object pool's AVL tree).
Issue #2398
This patch replaces the former use of size_t with the use of the
'Ram_quota' type to improve type safety (in particular to avoid
accidentally mixing up RAM quotas with cap quotas).
Issue #2398
The 'Ram_allocator' interface contains the subset of the RAM session
interface that is needed to satisfy the needs of the 'Heap' and
'Sliced_heap'. Its small size makes it ideal for intercepting memory
allocations as done by the new 'Constrained_ram_allocator' wrapper
class, which is meant to replace the existing 'base/allocator_guard.h'
and 'os/ram_session_guard.h'.
Issue #2398
This patch augments the existing session/session.h with useful types for
the session creation:
* The new 'Insufficient_ram_quota' and 'Insufficient_cap_quota'
exceptions are meant to supersede the old 'Quota_exceeded' exception
of the 'Parent' and 'Root' interfaces.
* The 'Session::Resources' struct subsumes the information about the
session quota provided by the client.
* The boolean 'Session::Diag' type will allow sessions to operate in a
diagnostic mode.
* The existing 'Session_label' is not also available under the alias
'Session::Label'.
* A few helper functions ease the extraction of typed session arguments
from the session-argument string.
Issue #2398
This accessor is useful to eagerly expand the slab with new slab blocks,
side stepping the slab's built-in policy for the allocation of new slab
blocks.
This is particularly important when using the slab for allocating the
cap space meta-data for the base-hw kernel. To guarantee that the slab
gets never exhausted in the kernel, it is expanded before entering the
kernel.
With the introduction of the 'Out_of_caps' exception type, the slab
needs to consider exceptions during the call of '_new_slab_block' by
reverting the 'nested' state.
