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minix/servers/vm/slaballoc.c
Ben Gras f78d8e74fd secondary cache feature in vm. 
A new call to vm lets processes yield a part of their memory to vm,
together with an id, getting newly allocated memory in return. vm is
allowed to forget about it if it runs out of memory. processes can ask
for it back using the same id. (These two operations are normally
combined in a single call.)

It can be used as a as-big-as-memory-will-allow block cache for
filesystems, which is how mfs now uses it.
2010-05-05 11:35:04 +00:00

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#define _SYSTEM 1
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/config.h>
#include <minix/const.h>
#include <minix/ds.h>
#include <minix/endpoint.h>
#include <minix/keymap.h>
#include <minix/minlib.h>
#include <minix/type.h>
#include <minix/ipc.h>
#include <minix/sysutil.h>
#include <minix/syslib.h>
#include <minix/bitmap.h>
#include <minix/debug.h>
#include <assert.h>
#include <errno.h>
#include <assert.h>
#include <string.h>
#include <env.h>
#include <memory.h>
#include "glo.h"
#include "proto.h"
#include "util.h"
#include "sanitycheck.h"
#define SLABSIZES 60
#define ITEMSPERPAGE(bytes) (DATABYTES / (bytes))
#define ELBITS (sizeof(element_t)*8)
#define BITPAT(b) (1UL << ((b) % ELBITS))
#define BITEL(f, b) (f)->sdh.usebits[(b)/ELBITS]
#define OFF(f, b) assert(!GETBIT(f, b))
#define ON(f, b) assert(GETBIT(f, b))
#if MEMPROTECT
#define SLABDATAWRITABLE(data, wr) do { \
assert(data->sdh.writable == WRITABLE_NONE); \
assert(wr != WRITABLE_NONE); \
vm_pagelock(data, 0); \
data->sdh.writable = wr; \
} while(0)
#define SLABDATAUNWRITABLE(data) do { \
assert(data->sdh.writable != WRITABLE_NONE); \
data->sdh.writable = WRITABLE_NONE; \
vm_pagelock(data, 1); \
} while(0)
#define SLABDATAUSE(data, code) do { \
SLABDATAWRITABLE(data, WRITABLE_HEADER); \
code \
SLABDATAUNWRITABLE(data); \
} while(0)
#else
#define SLABDATAWRITABLE(data, wr)
#define SLABDATAUNWRITABLE(data)
#define SLABDATAUSE(data, code) do { code } while(0)
#endif
#define GETBIT(f, b) (BITEL(f,b) & BITPAT(b))
#define SETBIT(f, b) {OFF(f,b); SLABDATAUSE(f, BITEL(f,b)|= BITPAT(b); (f)->sdh.nused++;); }
#define CLEARBIT(f, b) {ON(f, b); SLABDATAUSE(f, BITEL(f,b)&=~BITPAT(b); (f)->sdh.nused--; (f)->sdh.freeguess = (b);); }
#define MINSIZE 8
#define MAXSIZE (SLABSIZES-1+MINSIZE)
#define USEELEMENTS (1+(VM_PAGE_SIZE/MINSIZE/8))
PRIVATE int pages = 0;
typedef u8_t element_t;
#define BITS_FULL (~(element_t)0)
typedef element_t elements_t[USEELEMENTS];
/* This file is too low-level to have global SANITYCHECKs everywhere,
* as the (other) data structures are often necessarily in an
* inconsistent state during a slaballoc() / slabfree(). So only do
* our own sanity checks here, with SLABSANITYCHECK.
*/
/* Special writable values. */
#define WRITABLE_NONE -2
#define WRITABLE_HEADER -1
struct sdh {
#if SANITYCHECKS
u32_t magic1;
#endif
u8_t list;
u16_t nused; /* Number of data items used in this slab. */
int freeguess;
struct slabdata *next, *prev;
elements_t usebits;
phys_bytes phys;
#if SANITYCHECKS
int writable; /* data item number or WRITABLE_* */
u32_t magic2;
#endif
};
#define DATABYTES (VM_PAGE_SIZE-sizeof(struct sdh))
#define MAGIC1 0x1f5b842f
#define MAGIC2 0x8bb5a420
#define JUNK 0xdeadbeef
#define NOJUNK 0xc0ffee
#define LIST_UNUSED 0
#define LIST_FREE 1
#define LIST_USED 2
#define LIST_FULL 3
#define LIST_NUMBER 4
PRIVATE struct slabheader {
struct slabdata {
struct sdh sdh;
u8_t data[DATABYTES];
} *list_head[LIST_NUMBER];
} slabs[SLABSIZES];
FORWARD _PROTOTYPE( int objstats, (void *, int, struct slabheader **, struct slabdata **, int *));
#define GETSLAB(b, s) { \
int i; \
assert((b) >= MINSIZE); \
i = (b) - MINSIZE; \
assert((i) < SLABSIZES); \
assert((i) >= 0); \
s = &slabs[i]; \
}
#define LH(sl, l) (sl)->list_head[l]
/* move head of list l1 to list of l2 in slabheader sl. */
#define MOVEHEAD(sl, l1, l2) { \
struct slabdata *t; \
assert(LH(sl,l1)); \
REMOVEHEAD(sl, l1, t); \
ADDHEAD(t, sl, l2); \
}
/* remove head of list 'list' in sl, assign it unlinked to 'to'. */
#define REMOVEHEAD(sl, list, to) { \
struct slabdata *dat; \
dat = (to) = LH(sl, list); \
assert(dat); \
LH(sl, list) = dat->sdh.next; \
UNLINKNODE(dat); \
}
/* move slabdata nw to slabheader sl under list number l. */
#define ADDHEAD(nw, sl, l) { \
SLABDATAUSE(nw, \
(nw)->sdh.next = LH(sl, l); \
(nw)->sdh.prev = NULL; \
(nw)->sdh.list = l;); \
LH(sl, l) = (nw); \
if((nw)->sdh.next) { \
SLABDATAUSE((nw)->sdh.next, \
(nw)->sdh.next->sdh.prev = (nw);); \
} \
}
#define UNLINKNODE(node) { \
struct slabdata *next, *prev; \
prev = (node)->sdh.prev; \
next = (node)->sdh.next; \
if(prev) { SLABDATAUSE(prev, prev->sdh.next = next;); } \
if(next) { SLABDATAUSE(next, next->sdh.prev = prev;); } \
}
struct slabdata *newslabdata(int list)
{
struct slabdata *n;
phys_bytes p;
assert(sizeof(*n) == VM_PAGE_SIZE);
if(!(n = vm_allocpage(&p, VMP_SLAB))) {
printf("newslabdata: vm_allocpage failed\n");
return NULL;
}
memset(n->sdh.usebits, 0, sizeof(n->sdh.usebits));
pages++;
n->sdh.phys = p;
#if SANITYCHECKS
n->sdh.magic1 = MAGIC1;
n->sdh.magic2 = MAGIC2;
#endif
n->sdh.nused = 0;
n->sdh.freeguess = 0;
n->sdh.list = list;
#if SANITYCHECKS
n->sdh.writable = WRITABLE_HEADER;
SLABDATAUNWRITABLE(n);
#endif
return n;
}
#if SANITYCHECKS
/*===========================================================================*
* checklist *
*===========================================================================*/
PRIVATE int checklist(char *file, int line,
struct slabheader *s, int l, int bytes)
{
struct slabdata *n = s->list_head[l];
int ch = 0;
while(n) {
int count = 0, i;
#if SANITYCHECKS
MYASSERT(n->sdh.magic1 == MAGIC1);
MYASSERT(n->sdh.magic2 == MAGIC2);
#endif
MYASSERT(n->sdh.list == l);
MYASSERT(usedpages_add(n->sdh.phys, VM_PAGE_SIZE) == OK);
if(n->sdh.prev)
MYASSERT(n->sdh.prev->sdh.next == n);
else
MYASSERT(s->list_head[l] == n);
if(n->sdh.next) MYASSERT(n->sdh.next->sdh.prev == n);
for(i = 0; i < USEELEMENTS*8; i++)
if(i >= ITEMSPERPAGE(bytes))
MYASSERT(!GETBIT(n, i));
else
if(GETBIT(n,i))
count++;
MYASSERT(count == n->sdh.nused);
ch += count;
n = n->sdh.next;
}
return ch;
}
/*===========================================================================*
* void slab_sanitycheck *
*===========================================================================*/
PUBLIC void slab_sanitycheck(char *file, int line)
{
int s;
for(s = 0; s < SLABSIZES; s++) {
int l;
for(l = 0; l < LIST_NUMBER; l++) {
checklist(file, line, &slabs[s], l, s + MINSIZE);
}
}
}
/*===========================================================================*
* int slabsane *
*===========================================================================*/
PUBLIC int slabsane_f(char *file, int line, void *mem, int bytes)
{
struct slabheader *s;
struct slabdata *f;
int i;
return (objstats(mem, bytes, &s, &f, &i) == OK);
}
#endif
static int nojunkwarning = 0;
/*===========================================================================*
* void *slaballoc *
*===========================================================================*/
PUBLIC void *slaballoc(int bytes)
{
int i;
int count = 0;
struct slabheader *s;
struct slabdata *firstused;
SLABSANITYCHECK(SCL_FUNCTIONS);
/* Retrieve entry in slabs[]. */
GETSLAB(bytes, s);
assert(s);
/* To make the common case more common, make space in the 'used'
* queue first.
*/
if(!LH(s, LIST_USED)) {
/* Make sure there is something on the freelist. */
SLABSANITYCHECK(SCL_DETAIL);
if(!LH(s, LIST_FREE)) {
struct slabdata *nd = newslabdata(LIST_FREE);
SLABSANITYCHECK(SCL_DETAIL);
if(!nd) return NULL;
ADDHEAD(nd, s, LIST_FREE);
SLABSANITYCHECK(SCL_DETAIL);
}
SLABSANITYCHECK(SCL_DETAIL);
MOVEHEAD(s, LIST_FREE, LIST_USED);
SLABSANITYCHECK(SCL_DETAIL);
}
SLABSANITYCHECK(SCL_DETAIL);
assert(s);
firstused = LH(s, LIST_USED);
assert(firstused);
#if SANITYCHECKS
assert(firstused->sdh.magic1 == MAGIC1);
assert(firstused->sdh.magic2 == MAGIC2);
#endif
assert(firstused->sdh.nused < ITEMSPERPAGE(bytes));
for(i = firstused->sdh.freeguess;
count < ITEMSPERPAGE(bytes); count++, i++) {
SLABSANITYCHECK(SCL_DETAIL);
i = i % ITEMSPERPAGE(bytes);
if(!GETBIT(firstused, i)) {
struct slabdata *f;
char *ret;
SETBIT(firstused, i);
SLABSANITYCHECK(SCL_DETAIL);
if(firstused->sdh.nused == ITEMSPERPAGE(bytes)) {
SLABSANITYCHECK(SCL_DETAIL);
MOVEHEAD(s, LIST_USED, LIST_FULL);
SLABSANITYCHECK(SCL_DETAIL);
}
SLABSANITYCHECK(SCL_DETAIL);
ret = ((char *) firstused->data) + i*bytes;
#if SANITYCHECKS
#if MEMPROTECT
nojunkwarning++;
slabunlock(ret, bytes);
nojunkwarning--;
assert(!nojunkwarning);
#endif
*(u32_t *) ret = NOJUNK;
#if MEMPROTECT
slablock(ret, bytes);
#endif
#endif
SLABSANITYCHECK(SCL_FUNCTIONS);
SLABDATAUSE(firstused, firstused->sdh.freeguess = i+1;);
#if SANITYCHECKS
if(bytes >= SLABSIZES+MINSIZE) {
printf("slaballoc: odd, bytes %d?\n", bytes);
}
if(!slabsane_f(__FILE__, __LINE__, ret, bytes))
panic("slaballoc: slabsane failed");
#endif
return ret;
}
SLABSANITYCHECK(SCL_DETAIL);
}
SLABSANITYCHECK(SCL_FUNCTIONS);
panic("slaballoc: no space in 'used' slabdata");
/* Not reached. */
return NULL;
}
/*===========================================================================*
* int objstats *
*===========================================================================*/
PRIVATE int objstats(void *mem, int bytes,
struct slabheader **sp, struct slabdata **fp, int *ip)
{
#if SANITYCHECKS
#define OBJSTATSCHECK(cond) \
if(!(cond)) { \
printf("VM: objstats: %s failed for ptr 0x%p, %d bytes\n", \
#cond, mem, bytes); \
return EINVAL; \
}
#else
#define OBJSTATSCHECK(cond)
#endif
struct slabheader *s;
struct slabdata *f;
int i;
OBJSTATSCHECK((char *) mem >= (char *) VM_PAGE_SIZE);
#if SANITYCHECKS
if(*(u32_t *) mem == JUNK && !nojunkwarning) {
util_stacktrace();
printf("VM: WARNING: JUNK seen in slab object, likely freed\n");
}
#endif
/* Retrieve entry in slabs[]. */
GETSLAB(bytes, s);
/* Round address down to VM_PAGE_SIZE boundary to get header. */
f = (struct slabdata *) ((char *) mem - (vir_bytes) mem % VM_PAGE_SIZE);
#if SANITYCHECKS
OBJSTATSCHECK(f->sdh.magic1 == MAGIC1);
OBJSTATSCHECK(f->sdh.magic2 == MAGIC2);
#endif
OBJSTATSCHECK(f->sdh.list == LIST_USED || f->sdh.list == LIST_FULL);
/* Make sure it's in range. */
OBJSTATSCHECK((char *) mem >= (char *) f->data);
OBJSTATSCHECK((char *) mem < (char *) f->data + sizeof(f->data));
/* Get position. */
i = (char *) mem - (char *) f->data;
OBJSTATSCHECK(!(i % bytes));
i = i / bytes;
/* Make sure it is marked as allocated. */
OBJSTATSCHECK(GETBIT(f, i));
/* return values */
*ip = i;
*fp = f;
*sp = s;
return OK;
}
/*===========================================================================*
* void *slabfree *
*===========================================================================*/
PUBLIC void slabfree(void *mem, int bytes)
{
int i;
struct slabheader *s;
struct slabdata *f;
SLABSANITYCHECK(SCL_FUNCTIONS);
if(objstats(mem, bytes, &s, &f, &i) != OK) {
panic("slabfree objstats failed");
}
#if SANITYCHECKS
if(*(u32_t *) mem == JUNK) {
printf("VM: WARNING: likely double free, JUNK seen\n");
}
#endif
#if SANITYCHECKS
#if MEMPROTECT
slabunlock(mem, bytes);
#endif
*(u32_t *) mem = JUNK;
nojunkwarning++;
#if MEMPROTECT
slablock(mem, bytes);
#endif
nojunkwarning--;
assert(!nojunkwarning);
#endif
/* Free this data. */
CLEARBIT(f, i);
/* Check if this slab changes lists. */
if(f->sdh.nused == 0) {
/* Now become FREE; must've been USED */
assert(f->sdh.list == LIST_USED);
UNLINKNODE(f);
if(f == LH(s, LIST_USED))
LH(s, LIST_USED) = f->sdh.next;
ADDHEAD(f, s, LIST_FREE);
SLABSANITYCHECK(SCL_DETAIL);
} else if(f->sdh.nused == ITEMSPERPAGE(bytes)-1) {
/* Now become USED; must've been FULL */
assert(f->sdh.list == LIST_FULL);
UNLINKNODE(f);
if(f == LH(s, LIST_FULL))
LH(s, LIST_FULL) = f->sdh.next;
ADDHEAD(f, s, LIST_USED);
SLABSANITYCHECK(SCL_DETAIL);
} else {
/* Stay USED */
assert(f->sdh.list == LIST_USED);
}
SLABSANITYCHECK(SCL_FUNCTIONS);
return;
}
/*===========================================================================*
* void *slablock *
*===========================================================================*/
PUBLIC void slablock(void *mem, int bytes)
{
int i;
struct slabheader *s;
struct slabdata *f;
if(objstats(mem, bytes, &s, &f, &i) != OK)
panic("slablock objstats failed");
SLABDATAUNWRITABLE(f);
return;
}
/*===========================================================================*
* void *slabunlock *
*===========================================================================*/
PUBLIC void slabunlock(void *mem, int bytes)
{
int i;
struct slabheader *s;
struct slabdata *f;
if(objstats(mem, bytes, &s, &f, &i) != OK)
panic("slabunlock objstats failed");
SLABDATAWRITABLE(f, i);
return;
}
#if SANITYCHECKS
/*===========================================================================*
* void slabstats *
*===========================================================================*/
PUBLIC void slabstats(void)
{
int s, total = 0, totalbytes = 0;
static int n;
n++;
if(n%1000) return;
for(s = 0; s < SLABSIZES; s++) {
int l;
for(l = 0; l < LIST_NUMBER; l++) {
int b, t;
b = s + MINSIZE;
t = checklist(__FILE__, __LINE__, &slabs[s], l, b);
if(t > 0) {
int bytes = t * b;
printf("VMSTATS: %2d slabs: %d (%dkB)\n", b, t, bytes/1024);
totalbytes += bytes;
}
}
}
if(pages > 0) {
printf("VMSTATS: %dK net used in slab objects in %d pages (%dkB): %d%% utilization\n",
totalbytes/1024, pages, pages*VM_PAGE_SIZE/1024,
100 * totalbytes / (pages*VM_PAGE_SIZE));
}
}
#endif
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