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genode/repos/os/include/init/child.h
Martin Stein 8f9355b360 thread API & CPU session: accounting of CPU quota 
In the init configuration one can configure the donation of CPU time via
'resource' tags that have the attribute 'name' set to "CPU" and the
attribute 'quantum' set to the percentage of CPU quota that init shall
donate. The pattern is the same as when donating RAM quota.

! <start name="test">
!   <resource name="CPU" quantum="75"/>
! </start>

This would cause init to try donating 75% of its CPU quota to the child
"test".  Init and core do not preserve CPU quota for their own
requirements by default as it is done with RAM quota.

The CPU quota that a process owns can be applied through the thread
constructor. The constructor has been enhanced by an argument that
indicates the percentage of the programs CPU quota that shall be granted
to the new thread. So 'Thread(33, "test")' would cause the backing CPU
session to try to grant 33% of the programs CPU quota to the thread
"test". By now, the CPU quota of a thread can't be altered after
construction. Constructing a thread with CPU quota 0 doesn't mean the
thread gets never scheduled but that the thread has no guaranty to receive
CPU time. Such threads have to live with excess CPU time.

Threads that already existed in the official repositories of Genode were
adapted in the way that they receive a quota of 0.

This commit also provides a run test 'cpu_quota' in base-hw (the only
kernel that applies the CPU-quota scheme currently). The test basically
runs three threads with different physical CPU quota. The threads simply
count for 30 seconds each and the test then checks wether the counter
values relate to the CPU-quota distribution.

fix #1275
2014-11-28 12:02:37 +01:00

791 lines
24 KiB
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/*
* \brief Representation used for children of the init process
* \author Norman Feske
* \date 2010-05-04
*/
/*
* Copyright (C) 2010-2013 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__INIT__CHILD_H_
#define _INCLUDE__INIT__CHILD_H_
/* Genode includes */
#include <ram_session/connection.h>
#include <cpu_session/connection.h>
#include <cap_session/connection.h>
#include <base/printf.h>
#include <base/child.h>
/* init includes */
#include <init/child_config.h>
#include <init/child_policy.h>
namespace Init {
extern bool config_verbose;
/***************
** Utilities **
***************/
inline long read_priority(Genode::Xml_node start_node)
{
long priority = Genode::Cpu_session::DEFAULT_PRIORITY;
try { start_node.attribute("priority").value(&priority); }
catch (...) { }
/*
* All priority declarations in the config file are
* negative because child priorities can never be higher
* than parent priorities. To simplify priority
* calculations, we use inverted values. Lower values
* correspond to higher priorities.
*/
return -priority;
}
inline Genode::Affinity::Location
read_affinity_location(Genode::Affinity::Space const &space,
Genode::Xml_node start_node)
{
typedef Genode::Affinity::Location Location;
try {
Genode::Xml_node node = start_node.sub_node("affinity");
/* if no position value is specified, select the whole row/column */
unsigned long const
default_width = node.has_attribute("xpos") ? 1 : space.width(),
default_height = node.has_attribute("ypos") ? 1 : space.height();
unsigned long const
width = node.attribute_value<unsigned long>("width", default_width),
height = node.attribute_value<unsigned long>("height", default_height);
long const x1 = node.attribute_value<long>("xpos", 0),
y1 = node.attribute_value<long>("ypos", 0),
x2 = x1 + width - 1,
y2 = y1 + height - 1;
/* clip location to space boundary */
return Location(Genode::max(x1, 0L), Genode::max(y1, 0L),
Genode::min((unsigned)(x2 - x1 + 1), space.width()),
Genode::min((unsigned)(y2 - y1 + 1), space.height()));
}
catch (...) { return Location(0, 0, space.width(), space.height()); }
}
/**
* Return amount of RAM that is currently unused
*/
static inline Genode::size_t avail_slack_ram_quota()
{
Genode::size_t const preserve = 128*1024;
Genode::size_t const avail = Genode::env()->ram_session()->avail();
return avail > preserve ? avail - preserve : 0;
}
/**
* Return amount of CPU time that is currently unused
*/
static inline Genode::size_t avail_slack_cpu_quota() {
return Genode::env()->cpu_session()->avail(); }
/**
* Return true if service XML node matches the specified service name
*/
inline bool service_node_matches(Genode::Xml_node service_node, const char *service_name)
{
if (service_node.has_type("any-service"))
return true;
return service_node.has_type("service")
&& service_node.attribute("name").has_value(service_name);
}
/**
* Return sub string of label with the leading child name stripped out
*
*/
inline char const *skip_label_prefix(char const *child_name, char const *label)
{
Genode::size_t const child_name_len = Genode::strlen(child_name);
/*
* If the function was called with a valid "label" string, the
* following condition should be always satisfied. See the
* comment in 'service_node_args_condition_satisfied'.
*/
if (Genode::strcmp(child_name, label, child_name_len) == 0)
label += child_name_len;
/*
* If the original label was empty, the 'Child_policy_enforce_labeling'
* does not append a label separator after the child-name prefix. In
* this case, we resulting label is empty.
*/
if (*label == 0)
return label;
/*
* Skip label separator. This condition should be always satisfied.
*/
if (Genode::strcmp(" -> ", label, 4) == 0)
return label + 4;
PWRN("cannot skip label prefix while processing <if-arg>");
return label;
}
/**
* Check if arguments satisfy the condition specified for the route
*/
inline bool service_node_args_condition_satisfied(Genode::Xml_node service_node,
const char *args,
char const *child_name)
{
try {
Genode::Xml_node if_arg = service_node.sub_node("if-arg");
enum { KEY_MAX_LEN = 64, VALUE_MAX_LEN = 64 };
char key[KEY_MAX_LEN];
char value[VALUE_MAX_LEN];
if_arg.attribute("key").value(key, sizeof(key));
if_arg.attribute("value").value(value, sizeof(value));
char arg_value[VALUE_MAX_LEN];
Genode::Arg_string::find_arg(args, key).string(arg_value, sizeof(arg_value), "");
/*
* Skip child-name prefix if the key is the process "label".
*
* Because 'filter_session_args' is called prior the call of
* 'resolve_session_request' from the 'Child::session' function,
* 'args' contains the filtered arguments, in particular the label
* prefixed with the child's name. For the 'if-args' declaration,
* however, we want to omit specifying this prefix because the
* session route is specific to the named start node anyway. So
* the prefix information is redundant.
*/
if (Genode::strcmp("label", key) == 0)
return Genode::strcmp(value, skip_label_prefix(child_name, arg_value)) == 0;
return Genode::strcmp(value, arg_value) == 0;
} catch (...) { }
/* if no if-arg node exists, the condition is met */
return true;
}
/**
* Init-specific representation of a child service
*
* For init, we introduce this 'Service' variant that distinguishes two
* phases, declared and announced. A 'Routed_service' object is created
* when a '<provides>' declaration is found in init's configuration.
* At that time, however, no children including the server do yet exist.
* If, at this stage, a client tries to open a session to this service,
* the client get enqueued in a list of applicants and blocked. When
* the server officially announces its service and passes over the root
* capability, the 'Routed_service' enters the announced stage and any
* applicants get unblocked.
*/
class Routed_service : public Genode::Service
{
private:
Genode::Root_capability _root;
bool _announced;
Genode::Server *_server;
struct Applicant : public Genode::Cancelable_lock,
public Genode::List<Applicant>::Element
{
Applicant() : Cancelable_lock(Genode::Lock::LOCKED) { }
};
Genode::Lock _applicants_lock;
Genode::List<Applicant> _applicants;
public:
/**
* Constructor
*
* \param name name of service
* \param server server providing the service
*/
Routed_service(const char *name,
Genode::Server *server)
: Service(name), _announced(false), _server(server) { }
Genode::Server *server() const { return _server; }
void announce(Genode::Root_capability root)
{
Genode::Lock::Guard guard(_applicants_lock);
_root = root;
_announced = true;
/* wake up aspiring clients */
for (Applicant *a; (a = _applicants.first()); ) {
_applicants.remove(a);
a->unlock();
}
}
Genode::Session_capability session(const char *args,
Genode::Affinity const &affinity)
{
/*
* This function is called from the context of the client's
* activation thread. If the service is not yet announced,
* we let the client block.
*/
_applicants_lock.lock();
if (!_announced) {
Applicant myself;
_applicants.insert(&myself);
_applicants_lock.unlock();
myself.lock();
} else
_applicants_lock.unlock();
Genode::Session_capability cap;
try { cap = Genode::Root_client(_root).session(args, affinity); }
catch (Genode::Root::Invalid_args) { throw Invalid_args(); }
catch (Genode::Root::Unavailable) { throw Unavailable(); }
catch (Genode::Root::Quota_exceeded) { throw Quota_exceeded(); }
catch (Genode::Ipc_error) { throw Unavailable(); }
if (!cap.valid())
throw Unavailable();
return cap;
}
void upgrade(Genode::Session_capability sc, const char *args)
{
try { Genode::Root_client(_root).upgrade(sc, args); }
catch (Genode::Root::Invalid_args) { throw Invalid_args(); }
catch (Genode::Ipc_error) { throw Unavailable(); }
}
void close(Genode::Session_capability sc)
{
try { Genode::Root_client(_root).close(sc); }
catch (Genode::Ipc_error) { throw Genode::Blocking_canceled(); }
}
};
/**
* Interface for name database
*/
struct Name_registry
{
virtual ~Name_registry() { }
/**
* Check if specified name is unique
*
* \return false if name already exists
*/
virtual bool is_unique(const char *name) const = 0;
/**
* Find server with specified name
*/
virtual Genode::Server *lookup_server(const char *name) const = 0;
};
class Child_registry;
class Child : Genode::Child_policy
{
public:
/**
* Exception type
*/
class Child_name_is_not_unique { };
private:
friend class Child_registry;
Genode::List_element<Child> _list_element;
Genode::Xml_node _start_node;
Genode::Xml_node _default_route_node;
Name_registry *_name_registry;
/**
* Unique child name and file name of ELF binary
*/
struct Name
{
enum { MAX_NAME_LEN = 64 };
char file[MAX_NAME_LEN];
char unique[MAX_NAME_LEN];
/**
* Constructor
*
* Obtains file name and unique process name from XML node
*
* \param start_node XML start node
* \param registry registry tracking unique names
*/
Name(Genode::Xml_node start_node, Name_registry const *registry) {
try {
start_node.attribute("name").value(unique, sizeof(unique)); }
catch (Genode::Xml_node::Nonexistent_attribute) {
PWRN("Missing 'name' attribute in '<start>' entry.\n");
throw; }
/* check for a name confict with the other children */
if (!registry->is_unique(unique)) {
PERR("Child name \"%s\" is not unique", unique);
throw Child_name_is_not_unique();
}
/* use name as default file name if not declared otherwise */
Genode::strncpy(file, unique, sizeof(file));
/* check for a binary declaration */
try {
Genode::Xml_node binary = start_node.sub_node("binary");
binary.attribute("name").value(file, sizeof(file));
} catch (...) { }
}
} _name;
/**
* Platform-specific PD-session arguments
*/
struct Pd_args : Genode::Native_pd_args
{
Pd_args(Genode::Xml_node start_node);
} _pd_args;
struct Read_quota
{
void warn_unsuff_quota(Genode::size_t const avail)
{
using namespace Genode;
if (!config_verbose) { return; }
Genode::printf("Warning: Specified quota exceeds available quota.\n");
Genode::printf(" Proceeding with a quota of %zu.\n", avail);
}
Read_quota(Genode::Xml_node start_node, Genode::size_t & ram_quota,
Genode::size_t & cpu_quota)
{
Genode::Number_of_bytes ram_bytes = 0;
Genode::size_t cpu_percent = 0;
try {
Genode::Xml_node rsc = start_node.sub_node("resource");
for (;; rsc = rsc.next("resource")) {
try {
if (rsc.attribute("name").has_value("RAM")) {
rsc.attribute("quantum").value(&ram_bytes);
} else if (rsc.attribute("name").has_value("CPU")) {
rsc.attribute("quantum").value(&cpu_percent); }
} catch (...) { }
}
} catch (...) { }
ram_quota = ram_bytes;
cpu_quota = Genode::Cpu_session::pc_to_quota(cpu_percent);
/*
* If the configured RAM quota exceeds our own quota, we donate
* all remaining quota to the child but we need to count in
* our allocation of the child meta data from the heap.
* Hence, we preserve some of our own quota.
*/
Genode::size_t const ram_avail = avail_slack_ram_quota();
if (ram_quota > ram_avail) {
ram_quota = ram_avail;
warn_unsuff_quota(ram_avail);
}
Genode::size_t const cpu_avail = avail_slack_cpu_quota();
if (cpu_quota > cpu_avail) {
cpu_quota = cpu_avail;
warn_unsuff_quota(cpu_avail);
}
}
};
/**
* Resources assigned to the child
*/
struct Resources : Read_quota
{
long prio_levels_log2;
long priority;
Genode::Affinity affinity;
Genode::size_t ram_quota;
Genode::size_t cpu_quota;
Genode::Ram_connection ram;
Genode::Cpu_connection cpu;
Genode::Rm_connection rm;
Resources(Genode::Xml_node start_node, const char *label,
long prio_levels_log2,
Genode::Affinity::Space const &affinity_space)
:
Read_quota(start_node, ram_quota, cpu_quota),
prio_levels_log2(prio_levels_log2),
priority(read_priority(start_node)),
affinity(affinity_space,
read_affinity_location(affinity_space, start_node)),
ram(label),
cpu(label,
priority*(Genode::Cpu_session::PRIORITY_LIMIT >> prio_levels_log2),
affinity)
{
/* deduce session costs from usable ram quota */
Genode::size_t session_donations = Genode::Rm_connection::RAM_QUOTA +
Genode::Cpu_connection::RAM_QUOTA +
Genode::Ram_connection::RAM_QUOTA;
if (ram_quota > session_donations)
ram_quota -= session_donations;
else ram_quota = 0;
ram.ref_account(Genode::env()->ram_session_cap());
Genode::env()->ram_session()->transfer_quota(ram.cap(), ram_quota);
cpu.ref_account(Genode::env()->cpu_session_cap());
Genode::env()->cpu_session()->transfer_quota(cpu.cap(), cpu_quota);
}
} _resources;
/*
* Entry point used for serving the parent interface and the
* locally provided ROM sessions for the 'config' and 'binary'
* files.
*/
enum { ENTRYPOINT_STACK_SIZE = 12*1024 };
Genode::Rpc_entrypoint _entrypoint;
/**
* ELF binary
*/
Genode::Rom_connection _binary_rom;
Genode::Dataspace_capability _binary_rom_ds;
/**
* Private child configuration
*/
Init::Child_config _config;
/**
* Each child of init can act as a server
*/
Genode::Server _server;
Genode::Child _child;
Genode::Service_registry *_parent_services;
Genode::Service_registry *_child_services;
/**
* Policy helpers
*/
Init::Child_policy_enforce_labeling _labeling_policy;
Init::Child_policy_handle_cpu_priorities _priority_policy;
Init::Child_policy_provide_rom_file _config_policy;
Init::Child_policy_provide_rom_file _binary_policy;
Init::Child_policy_redirect_rom_file _configfile_policy;
Init::Child_policy_pd_args _pd_args_policy;
public:
Child(Genode::Xml_node start_node,
Genode::Xml_node default_route_node,
Name_registry *name_registry,
long prio_levels_log2,
Genode::Affinity::Space const &affinity_space,
Genode::Service_registry *parent_services,
Genode::Service_registry *child_services,
Genode::Cap_session *cap_session)
:
_list_element(this),
_start_node(start_node),
_default_route_node(default_route_node),
_name_registry(name_registry),
_name(start_node, name_registry),
_pd_args(start_node),
_resources(start_node, _name.unique, prio_levels_log2, affinity_space),
_entrypoint(cap_session, ENTRYPOINT_STACK_SIZE, _name.unique, false, _resources.affinity.location()),
_binary_rom(_name.file, _name.unique),
_binary_rom_ds(_binary_rom.dataspace()),
_config(_resources.ram.cap(), start_node),
_server(_resources.ram.cap()),
_child(_binary_rom_ds, _resources.ram.cap(),
_resources.cpu.cap(), _resources.rm.cap(), &_entrypoint, this),
_parent_services(parent_services),
_child_services(child_services),
_labeling_policy(_name.unique),
_priority_policy(_resources.prio_levels_log2, _resources.priority),
_config_policy("config", _config.dataspace(), &_entrypoint),
_binary_policy("binary", _binary_rom_ds, &_entrypoint),
_configfile_policy("config", _config.filename()),
_pd_args_policy(&_pd_args)
{
using namespace Genode;
if (_resources.ram_quota == 0)
PWRN("no valid RAM resource for child \"%s\"", _name.unique);
if (config_verbose) {
Genode::printf("child \"%s\"\n", _name.unique);
Genode::printf(" RAM quota: %zu\n", _resources.ram_quota);
Genode::printf(" ELF binary: %s\n", _name.file);
Genode::printf(" priority: %ld\n", _resources.priority);
}
/*
* Determine services provided by the child
*/
try {
Xml_node service_node = start_node.sub_node("provides").sub_node("service");
for (; ; service_node = service_node.next("service")) {
char name[Genode::Service::MAX_NAME_LEN];
service_node.attribute("name").value(name, sizeof(name));
if (config_verbose)
Genode::printf(" provides service %s\n", name);
child_services->insert(new (_child.heap())
Routed_service(name, &_server));
}
} catch (Xml_node::Nonexistent_sub_node) { }
}
virtual ~Child() {
Genode::Service *s;
while ((s = _child_services->find_by_server(&_server))) {
_child_services->remove(s);
}
}
/**
* Return true if the child has the specified name
*/
bool has_name(const char *n) const { return !Genode::strcmp(name(), n); }
Genode::Server *server() { return &_server; }
/**
* Start execution of child
*/
void start() { _entrypoint.activate(); }
/****************************
** Child-policy interface **
****************************/
const char *name() const { return _name.unique; }
Genode::Service *resolve_session_request(const char *service_name,
const char *args)
{
Genode::Service *service = 0;
/* check for config file request */
if ((service = _config_policy.resolve_session_request(service_name, args)))
return service;
/* check for binary file request */
if ((service = _binary_policy.resolve_session_request(service_name, args)))
return service;
try {
Genode::Xml_node route_node = _default_route_node;
try {
route_node = _start_node.sub_node("route"); }
catch (...) { }
Genode::Xml_node service_node = route_node.sub_node();
for (; ; service_node = service_node.next()) {
bool service_wildcard = service_node.has_type("any-service");
if (!service_node_matches(service_node, service_name))
continue;
if (!service_node_args_condition_satisfied(service_node, args, name()))
continue;
Genode::Xml_node target = service_node.sub_node();
for (; ; target = target.next()) {
if (target.has_type("parent")) {
service = _parent_services->find(service_name);
if (service)
return service;
if (!service_wildcard) {
PWRN("%s: service lookup for \"%s\" at parent failed", name(), service_name);
return 0;
}
}
if (target.has_type("child")) {
char server_name[Name::MAX_NAME_LEN];
server_name[0] = 0;
target.attribute("name").value(server_name, sizeof(server_name));
Genode::Server *server = _name_registry->lookup_server(server_name);
if (!server)
PWRN("%s: invalid route to non-existing server \"%s\"", name(), server_name);
service = _child_services->find(service_name, server);
if (service)
return service;
if (!service_wildcard) {
PWRN("%s: lookup to child service \"%s\" failed", name(), service_name);
return 0;
}
}
if (target.has_type("any-child")) {
if (_child_services->is_ambiguous(service_name)) {
PERR("%s: ambiguous routes to service \"%s\"", name(), service_name);
return 0;
}
service = _child_services->find(service_name);
if (service)
return service;
if (!service_wildcard) {
PWRN("%s: lookup for service \"%s\" failed", name(), service_name);
return 0;
}
}
if (target.is_last())
break;
}
}
} catch (...) {
PWRN("%s: no route to service \"%s\"", name(), service_name);
}
return service;
}
void filter_session_args(const char *service,
char *args, Genode::size_t args_len)
{
_labeling_policy. filter_session_args(service, args, args_len);
_priority_policy. filter_session_args(service, args, args_len);
_configfile_policy.filter_session_args(service, args, args_len);
_pd_args_policy. filter_session_args(service, args, args_len);
}
Genode::Affinity filter_session_affinity(Genode::Affinity const &session_affinity)
{
using namespace Genode;
Affinity::Space const &child_space = _resources.affinity.space();
Affinity::Location const &child_location = _resources.affinity.location();
/* check if no valid affinity space was specified */
if (session_affinity.space().total() == 0)
return Affinity(child_space, child_location);
Affinity::Space const &session_space = session_affinity.space();
Affinity::Location const &session_location = session_affinity.location();
/* scale resolution of resulting space */
Affinity::Space space(child_space.multiply(session_space));
/* subordinate session affinity to child affinity subspace */
Affinity::Location location(child_location
.multiply_position(session_space)
.transpose(session_location.xpos(),
session_location.ypos()));
return Affinity(space, location);
}
bool announce_service(const char *service_name,
Genode::Root_capability root,
Genode::Allocator *alloc,
Genode::Server *server)
{
if (config_verbose)
Genode::printf("child \"%s\" announces service \"%s\"\n",
name(), service_name);
Genode::Service *s = _child_services->find(service_name, &_server);
Routed_service *rs = dynamic_cast<Routed_service *>(s);
if (!s || !rs) {
PERR("%s: illegal announcement of service \"%s\"", name(), service_name);
return false;
}
rs->announce(root);
return true;
}
void resource_request(Genode::Parent::Resource_args const &args)
{
Genode::printf("child \"%s\" requests resources: %s\n",
name(), args.string());
Genode::size_t const requested_ram_quota =
Genode::Arg_string::find_arg(args.string(), "ram_quota")
.ulong_value(0);
if (avail_slack_ram_quota() < requested_ram_quota) {
PWRN("Cannot respond to resource request - out of memory");
return;
}
/*
* XXX Synchronize quota transfers from/to env()->ram_session()
*
* If multiple children issue concurrent resource requests, the
* value reported by 'avail_slack_ram_quota' may be out of date
* when calling 'transfer_quota'.
*/
Genode::env()->ram_session()->transfer_quota(_resources.ram.cap(),
requested_ram_quota);
/* wake up child that was starved for resources */
_child.notify_resource_avail();
}
Genode::Native_pd_args const *pd_args() const { return &_pd_args; }
};
}
#endif /* _INCLUDE__INIT__CHILD_H_ */
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