AsidManager Class Reference

#include <AsidManager.h>

Collaboration diagram for AsidManager:

Public Types
typedef uint8_t	Asid

Public Member Functions
Asid	obtainAsid ()
void	returnAsid (Asid asid)
void	bulldoze (Asid asid)

Static Public Member Functions
static AsidManager &	instance ()

Private Member Functions
	AsidManager ()
	~AsidManager ()

Private Attributes
uint32_t	m_Asids [NUM_ASID]
Mutex	m_Mutex

Static Private Attributes
static AsidManager	m_Instance

Detailed Description

MIPS TLB entries are marked with an ASID - an address space identifier. There are only 256 of these available (on the R4000) so they have to be managed in some way.

We have the policy that all processes in the "Ready" or "Running" state have ASIDs assigned. When a thread goes to sleep it must relinquish its ASID.

There is a use case where we have >256 running processes - This is handled by every process calling our function 'bulldoze' just before it is scheduled. Normally 'bulldoze' will do nothing, but in the case where there is contention for its ASID the entire TLB will be flushed of any entry containing that ASID.

Definition at line 44 of file AsidManager.h.

Member Typedef Documentation

typedef uint8_t AsidManager::Asid

ASID typedef

Definition at line 48 of file AsidManager.h.

Constructor & Destructor Documentation

AsidManager::AsidManager ( )

private

Default constructor

Definition at line 31 of file AsidManager.cc.

AsidManager::~AsidManager ( )

private

Destructor - not implemented.

Definition at line 35 of file AsidManager.cc.

Member Function Documentation

void AsidManager::bulldoze

(

AsidManager::Asid

asid

)

If the ASID given is contended, flush the TLB of all references to it.

Definition at line 87 of file AsidManager.cc.

Referenced by obtainAsid().

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AsidManager & AsidManager::instance ( )

static

Gets the instance of the AsidManager

Definition at line 26 of file AsidManager.cc.

References m_Instance.

AsidManager::Asid AsidManager::obtainAsid

(

)

Returns an ASID. The TLB is flushed of all references to that ASID.

Definition at line 39 of file AsidManager.cc.

References Semaphore::acquire(), bulldoze(), m_Asids, m_Mutex, panic(), and Semaphore::release().

void AsidManager::returnAsid

(

AsidManager::Asid

asid

)

Takes an ASID. The given ASID is returned to the pool of usable ASIDs.

Definition at line 75 of file AsidManager.cc.

References Semaphore::acquire(), ERROR, m_Asids, m_Mutex, and Semaphore::release().

Member Data Documentation

uint32_t AsidManager::m_Asids[NUM_ASID]

private

The array of ASID to instance count.

Definition at line 70 of file AsidManager.h.

Referenced by obtainAsid(), and returnAsid().

AsidManager AsidManager::m_Instance

staticprivate

The static AsidManager instance - singleton class.

Definition at line 76 of file AsidManager.h.

Referenced by instance().

Mutex AsidManager::m_Mutex

private

Our lock, to protect the integrity of our data.

Definition at line 73 of file AsidManager.h.

Referenced by obtainAsid(), and returnAsid().

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The documentation for this class was generated from the following files:

• AsidManager.h
• AsidManager.cc