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Matt Bishop Office: 2209 Watershed Sciences Phone: +1 (530) 752-8060 Email: mabishop@ucdavis.edu |
Version of April 1, 2022 at 12:53AM
This is the process table entry structure. There can be NPROC processes, so the table is of static size. This entry is always in core, even if the process is not running or is swapped out.
struct proc
{
char p_stat; /* process status */
char p_flag; /* process status attributes */
char p_pri; /* priority, negative is high */
char p_sig; /* signal number sent to this process */
char p_uid; /* user id, used to direct tty signals */
char p_time; /* resident time for scheduling */
char p_cpu; /* cpu usage for scheduling */
char p_nice; /* nice for scheduling */
int p_ttyp; /* controlling tty */
int p_pid; /* unique process id */
int p_ppid; /* process id of parent */
int p_addr; /* address of swappable image */
int p_size; /* size of swappable image (*64 bytes) */
int p_wchan; /* event process is awaiting */
int *p_textp; /* pointer to text structure */
} proc[NPROC];
/* stat codes */
#define SSLEEP 1 /* sleeping on high priority */
#define SWAIT 2 /* sleeping on low priority */
#define SRUN 3 /* running */
#define SIDL 4 /* intermediate state in process creation */
#define SZOMB 5 /* intermediate state in process termination */
#define SSTOP 6 /* process being traced */
/* flag codes */
#define SLOAD 01 /* in core */
#define SSYS 02 /* scheduling process */
#define SLOCK 04 /* process cannot be swapped */
#define SSWAP 010 /* process is being swapped out */
#define STRC 020 /* process is being traced */
#define SWTED 040 /* another tracing flag */
This is the remainder of the information about the process. It is kept in another area associated with the process. It need not stay in core when the process is swapped out to disk.
struct user
{
int u_rsav[2]; /* save r5,r6 when exchanging stacks */
int u_fsav[25]; /* save fp registers */
/* rsav and fsav must be first in structure */
char u_segflg; /* flag for IO; user or kernel space */
char u_error; /* return error code */
char u_uid; /* effective user id */
char u_gid; /* effective group id */
char u_ruid; /* real user id */
char u_rgid; /* real group id */
int u_procp; /* pointer to proc structure */
char *u_base; /* base address for IO */
char *u_count; /* bytes remaining for IO */
char *u_offset[2]; /* offset in file for IO */
int *u_cdir; /* pointer to inode of current directory */
char u_dbuf[DIRSIZ]; /* current pathname component */
char *u_dirp; /* current pointer to inode */
struct { /* current directory entry */
int u_ino; /* inode number */
char u_name[DIRSIZ]; /* name of directory */
} u_dent;
int *u_pdir; /* inode of parent directory of dirp */
int u_uisa[16]; /* prototype of segmentation addresses */
int u_uisd[16]; /* prototype of segmentation descriptors */
int u_ofile[NOFILE]; /* pointers to file structures of open files */
int u_arg[5]; /* arguments to current system call */
int u_tsize; /* text size (*64) */
int u_dsize; /* data size (*64) */
int u_ssize; /* stack size (*64) */
int u_sep; /* flag for I and D separation */
int u_qsav[2]; /* label variable for quits and interrupts */
int u_ssav[2]; /* label variable for swapping */
int u_signal[NSIG]; /* disposition of signals */
int u_utime; /* this process user time */
int u_stime; /* this process system time */
int u_cutime[2]; /* sum of childs' utimes */
int u_cstime[2]; /* sum of childs' stimes */
int *u_ar0; /* address of users saved R0 */
int u_prof[4]; /* profile arguments */
char u_intflg; /* catch intr from sys */
/* kernel stack per user
* extends from u + USIZE*64
* backward not to reach here
*/
} u;
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ECS 150, Operating Systems Version of April 1, 2022 at 12:53AM
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