bdec3dd668
The trace_fs server provides access to a Trace_session by using a
File_system_session as frontend.
Each trace subject is represented by a directory ('thread_name.subject')
that contains specific files ('active', 'cleanup', 'enable', 'events',
'buffer_size' and 'policy'), which are used to control the tracing
process of the thread as well as storing the content of its trace
buffer.
The tracing of a thread is only activated if there is a valid policy
installed and the intend to trace the subject was made clear by writing
'1' to the 'enable' file.
The tracing of a thread may be deactived by writing a '0' to the
'enable' file.
A policy may be changed by overwriting the currently used one. In this
case the old policy is replaced by the new policy and is automatically
utilize.
Writing a value to the 'buffer_size' file changes the appointed size of
the trace buffer. This value is only evaluted by reactivating the
tracing process.
The content of the trace buffer may be accessed by reading from the
'events' file. Throughout all tracing session new trace events are
appended to this file.
Nodes of UNTRACED subjects are kept as long as they do not change their
tracing state to DEAD. In this case all nodes are removed from the
file system. Subjects that were traced before and are now UNTRACED will
only be removed by writing '1' to the 'cleanup' file - even if they
are DEAD by now.
To use the trace_fs a config similar to the following may be used:
! <start name="trace_fs">
! <resource name="RAM" quantum="128M"/>
! <provides><service name="File_system"/></provides>
! <config>
! <policy label="noux -> trace" interval="1000" subject_limit="512" trace_quota="64M" />
! </config>
! </start>
'interval' sets the periode in which the Trace_session is polled. The
time is given in milliseconds.
'subject_limit' speficies how many trace subject should by acquired at
most when the Trace_session is polled.
'trace_quota' is the amount of quota the trace_fs should use for the
Trace_session connection. The remaing amount of RAM quota will be used
for the actual nodes of the file system and the 'policy' as well as the
'events' files.
In addiition there are 'buffer_size' and 'buffer_size_limit' that define
the initial and the upper limit of the size of a trace buffer.
Tracing of parent processes or rather threads may be enabled by setting
'parent_levels' to a value greater than '0' (though this attribute is
available, the trace session component within core still lacks support
for it).
A ready-to-use runscript can by found in 'ports/run/noux_trace_fs.run'.
Fixes #1049.
129 lines
2.4 KiB
C++
129 lines
2.4 KiB
C++
/*
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* \brief File-system node
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* \author Norman Feske
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* \date 2012-04-11
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*/
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#ifndef _NODE_H_
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#define _NODE_H_
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/* Genode includes */
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#include <util/list.h>
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#include <base/lock.h>
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#include <base/signal.h>
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namespace File_system {
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class Listener : public List<Listener>::Element
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{
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private:
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Lock _lock;
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Signal_context_capability _sigh;
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bool _marked_as_updated;
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public:
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Listener() : _marked_as_updated(false) { }
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Listener(Signal_context_capability sigh)
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: _sigh(sigh), _marked_as_updated(false) { }
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void notify()
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{
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Lock::Guard guard(_lock);
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if (_marked_as_updated && _sigh.valid())
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Signal_transmitter(_sigh).submit();
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_marked_as_updated = false;
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}
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void mark_as_updated()
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{
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Lock::Guard guard(_lock);
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_marked_as_updated = true;
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}
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bool valid() const { return _sigh.valid(); }
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};
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class Node : public List<Node>::Element
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{
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public:
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typedef char Name[128];
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private:
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Name _name;
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unsigned long const _inode;
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List<Listener> _listeners;
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bool _modified;
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/**
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* Generate unique inode number
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*/
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static unsigned long _unique_inode()
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{
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static unsigned long inode_count;
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return ++inode_count;
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}
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public:
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Node()
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: _inode(_unique_inode()), _modified(false)
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{ _name[0] = 0; }
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virtual ~Node()
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{
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/* propagate event to listeners */
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mark_as_updated();
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notify_listeners();
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while (_listeners.first())
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_listeners.remove(_listeners.first());
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}
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unsigned long inode() const { return _inode; }
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char const *name() const { return _name; }
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/**
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* Assign name
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*/
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void name(char const *name) { strncpy(_name, name, sizeof(_name)); }
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virtual size_t read(char *dst, size_t len, seek_off_t) = 0;
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virtual size_t write(char const *src, size_t len, seek_off_t) = 0;
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virtual Status status() const = 0;
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void add_listener(Listener *listener)
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{
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_listeners.insert(listener);
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}
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void remove_listener(Listener *listener)
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{
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_listeners.remove(listener);
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}
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void notify_listeners()
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{
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for (Listener *curr = _listeners.first(); curr; curr = curr->next())
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curr->notify();
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}
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void mark_as_updated()
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{
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for (Listener *curr = _listeners.first(); curr; curr = curr->next())
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curr->mark_as_updated();
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}
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};
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}
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#endif /* _NODE_H_ */
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