ref: a7f5ecaf636e38f407c951d0e86dcc4c4f424bd6
dir: /sys/src/cmd/venti/srv/icache.c/
#include "stdinc.h"
#include "dat.h"
#include "fns.h"
int icacheprefetch = 1;
typedef struct ICache ICache;
typedef struct IHash IHash;
typedef struct ISum ISum;
struct ICache
{
QLock lock;
Rendez full;
IHash *hash;
IEntry *entries;
int nentries;
IEntry free;
IEntry clean;
IEntry dirty;
u32int maxdirty;
u32int ndirty;
AState as;
ISum **sum;
int nsum;
IHash *shash;
IEntry *sentries;
int nsentries;
};
static ICache icache;
/*
* Hash table of IEntries
*/
struct IHash
{
int bits;
u32int size;
IEntry **table;
};
static IHash*
mkihash(int size1)
{
u32int size;
int bits;
IHash *ih;
bits = 0;
size = 1;
while(size < size1){
bits++;
size <<= 1;
}
ih = vtmallocz(sizeof(IHash)+size*sizeof(ih->table[0]));
ih->table = (IEntry**)(ih+1);
ih->bits = bits;
ih->size = size;
return ih;
}
static IEntry*
ihashlookup(IHash *ih, u8int score[VtScoreSize], int type)
{
u32int h;
IEntry *ie;
h = hashbits(score, ih->bits);
for(ie=ih->table[h]; ie; ie=ie->nexthash)
if((type == -1 || type == ie->ia.type) && scorecmp(score, ie->score) == 0)
return ie;
return nil;
}
static void
ihashdelete(IHash *ih, IEntry *ie, char *what)
{
u32int h;
IEntry **l;
h = hashbits(ie->score, ih->bits);
for(l=&ih->table[h]; *l; l=&(*l)->nexthash)
if(*l == ie){
*l = ie->nexthash;
return;
}
fprint(2, "warning: %s %V not found in ihashdelete\n", what, ie->score);
}
static void
ihashinsert(IHash *ih, IEntry *ie)
{
u32int h;
h = hashbits(ie->score, ih->bits);
ie->nexthash = ih->table[h];
ih->table[h] = ie;
}
/*
* IEntry lists.
*/
static IEntry*
popout(IEntry *ie)
{
if(ie->prev == nil && ie->next == nil)
return ie;
ie->prev->next = ie->next;
ie->next->prev = ie->prev;
ie->next = nil;
ie->prev = nil;
return ie;
}
static IEntry*
poplast(IEntry *list)
{
if(list->prev == list)
return nil;
return popout(list->prev);
}
static IEntry*
pushfirst(IEntry *list, IEntry *ie)
{
popout(ie);
ie->prev = list;
ie->next = list->next;
ie->prev->next = ie;
ie->next->prev = ie;
return ie;
}
/*
* Arena summary cache.
*/
struct ISum
{
QLock lock;
IEntry *entries;
int nentries;
int loaded;
u64int addr;
u64int limit;
Arena *arena;
int g;
};
static ISum*
scachelookup(u64int addr)
{
int i;
ISum *s;
for(i=0; i<icache.nsum; i++){
s = icache.sum[i];
if(s->addr <= addr && addr < s->limit){
if(i > 0){
memmove(icache.sum+1, icache.sum, i*sizeof icache.sum[0]);
icache.sum[0] = s;
}
return s;
}
}
return nil;
}
static void
sumclear(ISum *s)
{
int i;
for(i=0; i<s->nentries; i++)
ihashdelete(icache.shash, &s->entries[i], "scache");
s->nentries = 0;
s->loaded = 0;
s->addr = 0;
s->limit = 0;
s->arena = nil;
s->g = 0;
}
static ISum*
scacheevict(void)
{
ISum *s;
int i;
for(i=icache.nsum-1; i>=0; i--){
s = icache.sum[i];
if(canqlock(&s->lock)){
if(i > 0){
memmove(icache.sum+1, icache.sum, i*sizeof icache.sum[0]);
icache.sum[0] = s;
}
sumclear(s);
return s;
}
}
return nil;
}
static void
scachehit(u64int addr)
{
scachelookup(addr); /* for move-to-front */
}
static void
scachesetup(ISum *s, u64int addr)
{
u64int addr0, limit;
int g;
s->arena = amapitoag(mainindex, addr, &addr0, &limit, &g);
s->addr = addr0;
s->limit = limit;
s->g = g;
}
static void
scacheload(ISum *s)
{
int i, n;
s->loaded = 1;
n = asumload(s->arena, s->g, s->entries, ArenaCIGSize);
/*
* n can be less then ArenaCIGSize, either if the clump group
* is the last in the arena and is only partially filled, or if there
* are corrupt clumps in the group -- those are not returned.
*/
for(i=0; i<n; i++){
s->entries[i].ia.addr += s->addr;
ihashinsert(icache.shash, &s->entries[i]);
}
//fprint(2, "%T scacheload %s %d - %d entries\n", s->arena->name, s->g, n);
addstat(StatScachePrefetch, n);
s->nentries = n;
}
static ISum*
scachemiss(u64int addr)
{
ISum *s;
if(!icacheprefetch)
return nil;
s = scachelookup(addr);
if(s == nil){
/* first time: make an entry in the cache but don't populate it yet */
s = scacheevict();
if(s == nil)
return nil;
scachesetup(s, addr);
qunlock(&s->lock);
return nil;
}
/* second time: load from disk */
qlock(&s->lock);
if(s->loaded || !icacheprefetch){
qunlock(&s->lock);
return nil;
}
return s; /* locked */
}
/*
* Index cache.
*/
void
initicache(u32int mem0)
{
u32int mem;
int i, entries, scache;
icache.full.l = &icache.lock;
mem = mem0;
entries = mem / (sizeof(IEntry)+sizeof(IEntry*));
scache = (entries/8) / ArenaCIGSize;
entries -= entries/8;
if(scache < 4)
scache = 4;
if(scache > 16)
scache = 16;
if(entries < 1000)
entries = 1000;
fprint(2, "icache %,d bytes = %,d entries; %d scache\n", mem0, entries, scache);
icache.clean.prev = icache.clean.next = &icache.clean;
icache.dirty.prev = icache.dirty.next = &icache.dirty;
icache.free.prev = icache.free.next = &icache.free;
icache.hash = mkihash(entries);
icache.nentries = entries;
setstat(StatIcacheSize, entries);
icache.entries = vtmallocz(entries*sizeof icache.entries[0]);
icache.maxdirty = entries / 2;
for(i=0; i<entries; i++)
pushfirst(&icache.free, &icache.entries[i]);
icache.nsum = scache;
icache.sum = vtmallocz(scache*sizeof icache.sum[0]);
icache.sum[0] = vtmallocz(scache*sizeof icache.sum[0][0]);
icache.nsentries = scache * ArenaCIGSize;
icache.sentries = vtmallocz(scache*ArenaCIGSize*sizeof icache.sentries[0]);
icache.shash = mkihash(scache*ArenaCIGSize);
for(i=0; i<scache; i++){
icache.sum[i] = icache.sum[0] + i;
icache.sum[i]->entries = icache.sentries + i*ArenaCIGSize;
}
}
static IEntry*
evictlru(void)
{
IEntry *ie;
ie = poplast(&icache.clean);
if(ie == nil)
return nil;
ihashdelete(icache.hash, ie, "evictlru");
return ie;
}
static void
icacheinsert(u8int score[VtScoreSize], IAddr *ia, int state)
{
IEntry *ie;
if((ie = poplast(&icache.free)) == nil && (ie = evictlru()) == nil){
addstat(StatIcacheStall, 1);
while((ie = poplast(&icache.free)) == nil && (ie = evictlru()) == nil){
// Could safely return here if state == IEClean.
// But if state == IEDirty, have to wait to make
// sure we don't lose an index write.
// Let's wait all the time.
flushdcache();
kickicache();
rsleep(&icache.full);
}
addstat(StatIcacheStall, -1);
}
memmove(ie->score, score, VtScoreSize);
ie->state = state;
ie->ia = *ia;
if(state == IEClean){
addstat(StatIcachePrefetch, 1);
pushfirst(&icache.clean, ie);
}else{
addstat(StatIcacheWrite, 1);
assert(state == IEDirty);
icache.ndirty++;
setstat(StatIcacheDirty, icache.ndirty);
delaykickicache();
pushfirst(&icache.dirty, ie);
}
ihashinsert(icache.hash, ie);
}
int
icachelookup(u8int score[VtScoreSize], int type, IAddr *ia)
{
IEntry *ie;
qlock(&icache.lock);
addstat(StatIcacheLookup, 1);
if((ie = ihashlookup(icache.hash, score, type)) != nil){
*ia = ie->ia;
if(ie->state == IEClean)
pushfirst(&icache.clean, ie);
addstat(StatIcacheHit, 1);
qunlock(&icache.lock);
return 0;
}
if((ie = ihashlookup(icache.shash, score, type)) != nil){
*ia = ie->ia;
icacheinsert(score, &ie->ia, IEClean);
scachehit(ie->ia.addr);
addstat(StatScacheHit, 1);
qunlock(&icache.lock);
return 0;
}
addstat(StatIcacheMiss, 1);
qunlock(&icache.lock);
return -1;
}
int
insertscore(u8int score[VtScoreSize], IAddr *ia, int state, AState *as)
{
ISum *toload;
qlock(&icache.lock);
icacheinsert(score, ia, state);
if(state == IEClean)
toload = scachemiss(ia->addr);
else{
assert(state == IEDirty);
toload = nil;
if(as == nil)
fprint(2, "%T insertscore IEDirty without as; called from %#p\n",
getcallerpc(&score));
else{
if(icache.as.aa > as->aa)
fprint(2, "%T insertscore: aa moving backward: %#llux -> %#llux\n", icache.as.aa, as->aa);
icache.as = *as;
}
}
qunlock(&icache.lock);
if(toload){
scacheload(toload);
qunlock(&toload->lock);
}
if(icache.ndirty >= icache.maxdirty)
kickicache();
/*
* It's okay not to do this under icache.lock.
* Calling insertscore only happens when we hold
* the lump, meaning any searches for this block
* will hit in the lump cache until after we return.
*/
if(state == IEDirty)
markbloomfilter(mainindex->bloom, score);
return 0;
}
int
lookupscore(u8int score[VtScoreSize], int type, IAddr *ia)
{
int ms, ret;
IEntry d;
if(icachelookup(score, type, ia) >= 0){
addstat(StatIcacheRead, 1);
return 0;
}
ms = msec();
addstat(StatIcacheFill, 1);
if(loadientry(mainindex, score, type, &d) < 0)
ret = -1;
else{
ret = 0;
insertscore(score, &d.ia, IEClean, nil);
*ia = d.ia;
}
addstat2(StatIcacheRead, 1, StatIcacheReadTime, msec() - ms);
return ret;
}
u32int
hashbits(u8int *sc, int bits)
{
u32int v;
v = (sc[0] << 24) | (sc[1] << 16) | (sc[2] << 8) | sc[3];
if(bits < 32)
v >>= (32 - bits);
return v;
}
ulong
icachedirtyfrac(void)
{
return (vlong)icache.ndirty*IcacheFrac / icache.nentries;
}
/*
* Return a singly-linked list of dirty index entries.
* with 32-bit hash numbers between lo and hi
* and address < limit.
*/
IEntry*
icachedirty(u32int lo, u32int hi, u64int limit)
{
u32int h;
IEntry *ie, *dirty;
dirty = nil;
trace(TraceProc, "icachedirty enter");
qlock(&icache.lock);
for(ie = icache.dirty.next; ie != &icache.dirty; ie=ie->next){
if(ie->state == IEDirty && ie->ia.addr <= limit){
h = hashbits(ie->score, 32);
if(lo <= h && h <= hi){
ie->nextdirty = dirty;
dirty = ie;
}
}
}
qunlock(&icache.lock);
trace(TraceProc, "icachedirty exit");
if(dirty == nil)
flushdcache();
return dirty;
}
AState
icachestate(void)
{
AState as;
qlock(&icache.lock);
as = icache.as;
qunlock(&icache.lock);
return as;
}
/*
* The singly-linked non-circular list of index entries ie
* has been written to disk. Move them to the clean list.
*/
void
icacheclean(IEntry *ie)
{
IEntry *next;
trace(TraceProc, "icacheclean enter");
qlock(&icache.lock);
for(; ie; ie=next){
assert(ie->state == IEDirty);
next = ie->nextdirty;
ie->nextdirty = nil;
popout(ie); /* from icache.dirty */
icache.ndirty--;
ie->state = IEClean;
pushfirst(&icache.clean, ie);
}
setstat(StatIcacheDirty, icache.ndirty);
rwakeupall(&icache.full);
qunlock(&icache.lock);
trace(TraceProc, "icacheclean exit");
}
void
emptyicache(void)
{
int i;
IEntry *ie;
ISum *s;
qlock(&icache.lock);
while((ie = evictlru()) != nil)
pushfirst(&icache.free, ie);
for(i=0; i<icache.nsum; i++){
s = icache.sum[i];
qlock(&s->lock);
sumclear(s);
qunlock(&s->lock);
}
qunlock(&icache.lock);
}