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mmanage.c
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mmanage.c
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/**
* @file mmanage.c
* @author Prof. Dr. Wolfgang Fohl, HAW Hamburg
* @date 2014
* @brief Memory Manager module of TI BSP A3 virtual memory
*
* This is the memory manager process that
* works together with the vmaccess process to
* manage virtual memory management.
*
* The memory manager process will be invoked
* via a SIGUSR1 signal. It maintains the page table
* and provides the data pages in shared memory.
*
* This process starts shared memory, so
* it has to be started prior to the vmaccess process.
*
*/
#include "mmanage.h"
#include "debug.h"
#include "pagefile.h"
#include "logger.h"
#include "vmem.h"
/*
* Signatures of private / static functions
*/
/**
*****************************************************************************************
* @brief This function fetchs a page out of the pagefile.
*
* It is mainly a wrapper of the corresponding function of module pagefile.c
*
* @param pt_idx Index of the page that should be fetched.
*
* @return void
****************************************************************************************/
static void fetch_page(int pt_idx);
/**
*****************************************************************************************
* @brief This function writes a page into the pagefile.
*
* It is mainly a wrapper of the corresponding function of module pagefile.c
*
* @param pt_idx Index of the page that should be written into the pagefile.
*
* @return void
****************************************************************************************/
static void store_page(int pt_idx);
/**
*****************************************************************************************
* @brief This function initializes the virtual memory.
*
* In particular it creates the shared memory. The application just attachs to the
* shared memory.
*
* @return void
****************************************************************************************/
static void vmem_init(void);
/**
*****************************************************************************************
* @brief This function finds an unused frame.
*
* The framepage array of pagetable marks unused frames with VOID_IDX.
* Based on this information find_free_frame searchs in vmem->pt.framepage for the
* free frame with the smallest frame number.
*
* @return idx of the unused frame with the smallest idx.
* If all frames are in use, VOID_IDX will be returned.
****************************************************************************************/
static int find_free_frame();
/**
*****************************************************************************************
* @brief This function update the page table for page vmem->adm.req_pageno.
* It will be stored in frame.
*
* @param frame The frame that stores the now allocated page vmem->adm.req_pageno.
*
* @return void
****************************************************************************************/
static void update_pt(int frame);
/**
*****************************************************************************************
* @brief This function allocates a new page into memory. If all frames are in
* use the corresponding page replacement algorithm will be called.
*
* allocate_page gets the requested page via vmem->adm.req_pageno. Please take into
* account that allocate_page must update the page table and log the page fault
* as well.
* allocate_page does all actions that must be down when the SIGUSR1 signal
* indicates a page fault.
*
* @return void
****************************************************************************************/
static void allocate_page(void);
/**
*****************************************************************************************
* @brief This function is the signal handler attached to system call sigaction
* for signal SIGUSR1, SIGUSR2 aund SIGINT.
*
* These three signals have the same signal handler. Based on the parameter signo the
* corresponding action will be started.
*
* @param signo Current signal that has be be handled.
*
* @return void
****************************************************************************************/
static void sighandler(int signo);
/**
*****************************************************************************************
* @brief This function dumps the page table to stderr.
*
* @return void
****************************************************************************************/
static void dump_pt(void);
/**
*****************************************************************************************
* @brief This function implements page replacement algorithm aging.
*
* @return idx of the page that should be replaced.
****************************************************************************************/
static int find_remove_aging(void);
/**
*****************************************************************************************
* @brief This function implements page replacement algorithm fifo.
*
* @return idx of the page that should be replaced.
****************************************************************************************/
static int find_remove_fifo(void);
/**
*****************************************************************************************
* @brief This function implements page replacement algorithm clock.
*
* @return idx of the page that should be replaced.
****************************************************************************************/
static int find_remove_clock(void);
/**
*****************************************************************************************
* @brief This function selects and starts a page replacement algorithm.
*
* It is just a wrapper for the three page replacement algorithms.
*
* @return The idx of the page that should be replaced.
****************************************************************************************/
static int find_remove_frame(void);
/**
*****************************************************************************************
* @brief This function cleans up when mmange runs out.
*
* @return void
****************************************************************************************/
static void cleanup(void);
/**
*****************************************************************************************
* @brief This function scans all parameters of the porgram.
* The corresponding global variables vmem->adm.page_rep_algo will be set.
*
* @param argc number of parameter
*
* @param argv parameter list
*
* @return void
****************************************************************************************/
static void scan_params(int argc, char **argv);
/**
*****************************************************************************************
* @brief This function prints an error message and the usage information of
* this program.
*
* @param err_str pointer to the error string that should be printed.
*
* @return void
****************************************************************************************/
static void print_usage_info_and_exit(char *err_str);
/*
* variables
*/
static struct vmem_struct *vmem = NULL; //!< Reference to shared memory
static int signal_number = 0; //!< Number of signal received last
static sem_t *local_sem; //!< OS-X Named semaphores will be stored locally due to pointer
static int oldFrame = -1;
struct logevent event;
int clockpointer=0;
int sharedMemoryId;
int main(int argc, char **argv) {
struct sigaction sigact;
init_pagefile(); // init page file
open_logger(); // open logfile
/* Create shared memory and init vmem structure */
vmem_init();
TEST_AND_EXIT_ERRNO(!vmem, "Error initialising vmem");
PRINT_DEBUG((stderr, "vmem successfully created\n"));
// scan parameter
vmem->adm.program_name = argv[0];
vmem->adm.page_rep_algo = VMEM_ALGO_AGING;
scan_params(argc, argv);
/* Setup signal handler */
sigact.sa_handler = sighandler;
sigemptyset(&sigact.sa_mask);
sigact.sa_flags = 0;
TEST_AND_EXIT_ERRNO(sigaction(SIGUSR1, &sigact, NULL) == -1,
"Error installing signal handler for USR1");
PRINT_DEBUG((stderr, "USR1 handler successfully installed\n"));
TEST_AND_EXIT_ERRNO(sigaction(SIGUSR2, &sigact, NULL) == -1,
"Error installing signal handler for USR2");
PRINT_DEBUG((stderr, "USR2 handler successfully installed\n"));
TEST_AND_EXIT_ERRNO(sigaction(SIGINT, &sigact, NULL) == -1,
"Error installing signal handler for INT");
PRINT_DEBUG((stderr, "INT handler successfully installed\n"));
/* Signal processing loop */
while (1) {
signal_number = 0;
pause();
if (signal_number == SIGUSR1) { /* Page fault */
PRINT_DEBUG((stderr, "Processed SIGUSR1\n"));
signal_number = 0;
} else if (signal_number == SIGUSR2) { /* PT dump */
PRINT_DEBUG((stderr, "Processed SIGUSR2\n"));
signal_number = 0;
} else if (signal_number == SIGINT) {
PRINT_DEBUG((stderr, "Processed SIGINT\n"));
}
}
return 0;
}
void scan_params(int argc, char **argv) {
int i = 0;
unsigned char param_ok = FALSE;
// scan all parameters (argv[0] points to program name)
if (argc > 2)
print_usage_info_and_exit("Wrong number of parameters.\n");
for (i = 1; i < argc; i++) {
param_ok = FALSE;
if (0 == strcasecmp("-fifo", argv[i])) {
// page replacement strategies fifo selected
vmem->adm.page_rep_algo = VMEM_ALGO_FIFO;
param_ok = TRUE;
}
if (0 == strcasecmp("-clock", argv[i])) {
// page replacement strategies clock selected
vmem->adm.page_rep_algo = VMEM_ALGO_CLOCK;
param_ok = TRUE;
}
if (0 == strcasecmp("-aging", argv[i])) {
// page replacement strategies aging selected
vmem->adm.page_rep_algo = VMEM_ALGO_AGING;
param_ok = TRUE;
}
if (!param_ok)
print_usage_info_and_exit("Undefined parameter.\n"); // undefined parameter found
} // for loop
}
void print_usage_info_and_exit(char *err_str) {
fprintf(stderr, "Wrong parameter: %s\n", err_str);
fprintf(stderr, "Usage : %s [OPTIONS]\n", vmem->adm.program_name);
fprintf(stderr, " -fifo : Fifo page replacement algorithm.\n");
fprintf(stderr, " -clock : Clock page replacement algorithm.\n");
fprintf(stderr, " -aging : Aging page replacement algorithm.\n");
fprintf(stderr, " -pagesize=[8,16,32,64] : Page size.\n");
fflush(stderr);
exit(EXIT_FAILURE);
}
void sighandler(int signo) {
signal_number = signo;
if (signo == SIGUSR1) {
allocate_page();
sem_post(local_sem);
} else if (signo == SIGUSR2) {
dump_pt();
} else if (signo == SIGINT) {
cleanup();
exit(EXIT_SUCCESS);
}
}
/* Your code goes here... */
void vmem_init(void) {
int i;
// initialize Shared Memory
int shMemId = shmget(ftok(SHMKEY, SHMPROCID), sizeof(struct vmem_struct), IPC_CREAT | 0666);
if (shMemId < 0) {
perror("mmanage.c kann shared memory nicht erstellen");
exit(1);
}
vmem = (struct vmem_struct *) shmat(shMemId, 0, 0);
if (vmem < 0) {
perror("mmanage.c kann shared memory nicht erstellen");
exit(1);
}
// Initilize Administration Struct
vmem->adm.size = VMEM_VIRTMEMSIZE;
vmem->adm.mmanage_pid = getpid();
vmem->adm.shm_id = shMemId;
vmem->adm.req_pageno = 0;
vmem->adm.next_alloc_idx = 0;
vmem->adm.pf_count = 0;
vmem->adm.g_count = 0;
// Initilize page frame table
for (i = 0; i < VMEM_NPAGES; i++) {
vmem->pt.entries[i].flags = 0;
vmem->pt.entries[i].frame = VOID_IDX;
vmem->pt.entries[i].count = 0;
vmem->pt.entries[i].age = 0;
}
// initialize frames
for (i = 0; i < VMEM_NPAGES; i++) {
vmem->pt.framepage[i] = VOID_IDX;
}
// Initilize frames main memory
for (i = 0; i < VMEM_NFRAMES * VMEM_PAGESIZE; i++) {
vmem->data[i] = 0;
}
//Initilize Semaphore
local_sem = sem_open(NAMED_SEM, O_CREAT, 0777, 0);
if (local_sem < 0) {
perror("mmanage.c Semaphore kann nicht erstellt werden");
exit(1);
}
}
int find_free_frame() {
int freeFrame = VOID_IDX;
int i;
for (i=0; i<VMEM_NFRAMES; i++) {
if (vmem->pt.framepage[i] == VOID_IDX) { // sucht nach erstes freien frame
freeFrame = i;
break;
}
}
return freeFrame;
}
void allocate_page(void) {
int framenumb;
vmem->adm.pf_count++;
framenumb = find_free_frame();
// wenn alle Frames schon besetzt -> löschen ein frame
if (framenumb == VOID_IDX) {
framenumb = find_remove_frame();
}
vmem->adm.next_alloc_idx = framenumb;
update_pt(framenumb);
// "Pagefault" note
event.alloc_frame=vmem->adm.next_alloc_idx;
event.g_count=vmem->adm.g_count;
event.pf_count=vmem->adm.pf_count;
event.req_pageno=vmem->adm.req_pageno;
logger(event);
}
void fetch_page(int pt_idx) {
int* dataStart = &(vmem->data[vmem->adm.next_alloc_idx * VMEM_PAGESIZE]);
fetch_page_from_pagefile(pt_idx, dataStart);
}
void store_page(int pt_idx) {
int* dataStart = &(vmem->data[vmem->adm.next_alloc_idx * VMEM_PAGESIZE]);
store_page_to_pagefile(pt_idx, dataStart);
}
void update_pt(int frame) {
int mBit; //mod bit
int pagenumb = vmem->adm.req_pageno;
// alte Seite aus dem Frame löschen
int oldPage = vmem->pt.framepage[frame];
event.replaced_page=oldPage;
if(oldPage != VOID_IDX){
vmem->pt.entries[oldPage].frame = VOID_IDX;
}
// die Seite in File schreiben, wenn notwendig
mBit = vmem->pt.entries[oldPage].flags & PTF_DIRTY;
if (oldPage != VOID_IDX && mBit == PTF_DIRTY) {
store_page(oldPage);
vmem->pt.entries[oldPage].flags -= PTF_DIRTY;
}
//neue Seite laden
fetch_page(pagenumb);
vmem->pt.entries[pagenumb].frame = frame;
vmem->pt.entries[pagenumb].age=DEF_AGE;
vmem->pt.framepage[frame] = pagenumb;
}
//
int find_remove_frame(void) {
int framenumb = VOID_IDX;
switch (vmem->adm.page_rep_algo) { // suche nach bestimmte Algorithmus
case VMEM_ALGO_FIFO:
framenumb= find_remove_fifo();
break;
case VMEM_ALGO_AGING:
framenumb=find_remove_aging();
break;
case VMEM_ALGO_CLOCK:
framenumb=find_remove_clock();
break;
}
return framenumb;
}
// fifo alg
int find_remove_fifo(void) {
oldFrame = (oldFrame + 1) % VMEM_NFRAMES;
return oldFrame;
}
//aging
int find_remove_aging(void) {
int removeableFrame = 0;
int younger = MAX_AGE;
int page; // Seite, die im Frame liegt
int i;
for (i=0; i<VMEM_NFRAMES; i++)
{
page = vmem->pt.framepage[i];
if (vmem->pt.entries[page].age <= younger) { // suche jungste Frame
younger = vmem->pt.entries[page].age;
removeableFrame = i;
}
}
return removeableFrame;
}
//clock algo
int find_remove_clock(void) {
int page; //Seite, die im Frame liegt
int rBit; //ref bit
while(1) { // sucht passendes Frame um zu löschen
oldFrame = (oldFrame + 1) % VMEM_NFRAMES;
page = vmem->pt.framepage[oldFrame];
rBit = vmem->pt.entries[page].flags & PTF_REF;
if (rBit == 0) {
break; // to remove
} else {
vmem->pt.entries[page].flags = vmem->pt.entries[page].flags ^ rBit; // setze das R Bit auf "0"
}
}
return oldFrame;
}
void cleanup(void) {
sem_close(local_sem);
shmctl(vmem->adm.shm_id, IPC_RMID, 0); //shm zerstören
}
void dump_pt(void) {
int i;
printf("%d. Pagefault\n", vmem->adm.pf_count);
for (i=0; i<VMEM_NFRAMES; i++) {
printf("Frame; %d, Page: %d\n", i, vmem->pt.framepage[i]);
}
}
// EOF