devswap: simplify, don't panic when writing swapfile fails
always start the pager kproc in swapinit(), simplifying kickpager(). allow zero conf.nswap and conf.nswppo. avoid allocating the reference map and iolist arrays in that case. use ulong for ioptr and iolist indices. don't panic when writing pages out to the swapfile fails. just requeue the page in the io transaction list so we will try again next time executeio() is run or just free the page when the swap reference was dropped. remove unused pagersummary() function.
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parent
4b2f31131a
commit
26d36c3ae2
2 changed files with 34 additions and 43 deletions
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@ -23,23 +23,35 @@ static uchar *swapbuf;
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static AESstate *swapkey;
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static Page **iolist;
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static int ioptr;
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static ulong ioptr;
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static ushort ageclock;
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static void
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swapinit(void)
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{
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swapalloc.swmap = xalloc(conf.nswap);
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while(conf.nswap && conf.nswppo){
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swapalloc.swmap = xalloc(conf.nswap);
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if(swapalloc.swmap == nil)
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break;
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iolist = xalloc(conf.nswppo*sizeof(Page*));
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if(iolist == nil){
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xfree(swapalloc.swmap);
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swapalloc.swmap = nil;
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}
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break;
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}
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if(swapalloc.swmap == nil || iolist == nil)
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conf.nswap = conf.nswppo = 0;
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swapalloc.top = &swapalloc.swmap[conf.nswap];
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swapalloc.alloc = swapalloc.swmap;
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swapalloc.last = swapalloc.swmap;
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swapalloc.free = conf.nswap;
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swapalloc.xref = 0;
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iolist = xalloc(conf.nswppo*sizeof(Page*));
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if(swapalloc.swmap == nil || iolist == nil)
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panic("swapinit: not enough memory");
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kproc("pager", pager, 0);
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}
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static uintptr
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@ -116,12 +128,7 @@ swapcount(uintptr daddr)
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void
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kickpager(void)
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{
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static Ref started;
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if(started.ref || incref(&started) != 1)
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wakeup(&swapalloc.r);
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else
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kproc("pager", pager, 0);
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wakeup(&swapalloc.r);
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}
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static int
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@ -204,7 +211,7 @@ pager(void*)
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}
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qunlock(&p->seglock);
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if(ioptr > 0) {
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if(ioptr) {
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up->psstate = "I/O";
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executeio();
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}
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@ -331,28 +338,13 @@ pagepte(int type, Page **pg)
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}
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}
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void
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pagersummary(void)
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{
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print("%lud/%lud memory %lud/%lud swap %d iolist\n",
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palloc.user-palloc.freecount,
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palloc.user, conf.nswap-swapalloc.free, conf.nswap,
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ioptr);
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}
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static void
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executeio(void)
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{
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Page *outp;
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int i, n;
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Chan *c;
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char *kaddr;
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KMap *k;
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ulong i, j;
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c = swapimage.c;
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for(i = 0; i < ioptr; i++) {
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if(ioptr > conf.nswppo)
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panic("executeio: ioptr %d > %d", ioptr, conf.nswppo);
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for(i = j = 0; i < ioptr; i++) {
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outp = iolist[i];
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assert(outp->ref > 0);
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@ -361,16 +353,15 @@ executeio(void)
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/* only write when swap address still in use */
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if(swapcount(outp->daddr) > 1){
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k = kmap(outp);
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kaddr = (char*)VA(k);
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if(waserror())
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panic("executeio: page outp I/O error");
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n = devtab[c->type]->write(c, kaddr, BY2PG, outp->daddr);
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if(n != BY2PG)
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nexterror();
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Chan *c = swapimage.c;
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KMap *k = kmap(outp);
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if(waserror()){
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kunmap(k);
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iolist[j++] = outp;
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continue;
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}
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if(devtab[c->type]->write(c, (char*)VA(k), BY2PG, outp->daddr) != BY2PG)
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error(Eshort);
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kunmap(k);
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poperror();
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}
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@ -381,7 +372,8 @@ executeio(void)
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/* Free up the page after I/O */
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putpage(outp);
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}
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ioptr = 0;
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ioptr = j;
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if(j) print("executeio (%lud/%lud): %s\n", j, i, up->errstr);
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}
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int
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@ -416,9 +408,9 @@ setswapchan(Chan *c)
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n = devtab[c->type]->stat(c, buf, sizeof buf);
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if(n <= 0 || convM2D(buf, n, &d, nil) == 0)
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error("stat failed in setswapchan");
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if(d.length < conf.nswppo*BY2PG)
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if(d.length < (vlong)conf.nswppo*BY2PG)
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error("swap device too small");
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if(d.length < conf.nswap*BY2PG){
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if(d.length < (vlong)conf.nswap*BY2PG){
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conf.nswap = d.length/BY2PG;
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swapalloc.top = &swapalloc.swmap[conf.nswap];
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swapalloc.free = conf.nswap;
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@ -208,7 +208,6 @@ void pagechainhead(Page*);
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void pageinit(void);
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ulong pagenumber(Page*);
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ulong pagereclaim(Image*, ulong);
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void pagersummary(void);
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void panic(char*, ...);
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Cmdbuf* parsecmd(char *a, int n);
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void pathclose(Path*);
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