when i shuffled the locking in pools around, page colouring was
left behind.
page colouring is where you offset items within a page if you have
enough slack space. the previous implementation simply incremented
the colour so each new page got the next offset. i didnt do this
because the page and its items are now initted outside the lock,
so maintaining that curcolour iterator wasnt as easy.
this sidesteps the curcolor maintenance by just having each page
randomly pick a colour when it's set up.
tests? ok?
Index: kern/subr_pool.c
===================================================================
RCS file: /cvs/src/sys/kern/subr_pool.c,v
retrieving revision 1.163
diff -u -p -r1.163 subr_pool.c
--- kern/subr_pool.c 13 Oct 2014 00:12:51 -0000 1.163
+++ kern/subr_pool.c 28 Oct 2014 03:05:50 -0000
@@ -299,8 +299,7 @@ pool_init(struct pool *pp, size_t size,
*/
space = POOL_INPGHDR(pp) ? pp->pr_phoffset : pp->pr_pgsize;
space -= pp->pr_itemsperpage * pp->pr_size;
- pp->pr_maxcolor = (space / align) * align;
- pp->pr_curcolor = 0;
+ pp->pr_maxcolors = (space / align) + 1;
pp->pr_nget = 0;
pp->pr_nfail = 0;
@@ -750,6 +749,8 @@ pool_p_alloc(struct pool *pp, int flags)
XSIMPLEQ_INIT(&ph->ph_itemlist);
ph->ph_page = addr;
+ ph->ph_colored = addr +
+ arc4random_uniform(pp->pr_maxcolors) * pp->pr_align;
ph->ph_nmissing = 0;
arc4random_buf(&ph->ph_magic, sizeof(ph->ph_magic));
#ifdef DIAGNOSTIC
@@ -760,6 +761,7 @@ pool_p_alloc(struct pool *pp, int flags)
CLR(ph->ph_magic, POOL_MAGICBIT);
#endif /* DIAGNOSTIC */
+ addr = ph->ph_colored;
n = pp->pr_itemsperpage;
while (n--) {
pi = (struct pool_item *)addr;
@@ -996,8 +998,8 @@ pool_print_pagelist(struct pool_pagelist
struct pool_item *pi;
LIST_FOREACH(ph, pl, ph_pagelist) {
- (*pr)("\t\tpage %p, nmissing %d\n",
- ph->ph_page, ph->ph_nmissing);
+ (*pr)("\t\tpage %p, color %p, nmissing %d\n",
+ ph->ph_page, ph->ph_colored, ph->ph_nmissing);
XSIMPLEQ_FOREACH(pi, &ph->ph_itemlist, pi_list) {
if (pi->pi_magic != POOL_IMAGIC(ph, pi)) {
(*pr)("\t\t\titem %p, magic 0x%lx\n",
@@ -1021,8 +1023,8 @@ pool_print1(struct pool *pp, const char
modif++;
}
- (*pr)("POOL %s: size %u, align %u, roflags 0x%08x\n",
- pp->pr_wchan, pp->pr_size, pp->pr_align,
+ (*pr)("POOL %s: size %u, align %u, maxcolors %u, roflags 0x%08x\n",
+ pp->pr_wchan, pp->pr_size, pp->pr_align, pp->pr_maxcolors,
pp->pr_roflags);
(*pr)("\talloc %p\n", pp->pr_alloc);
(*pr)("\tminitems %u, minpages %u, maxpages %u, npages %u\n",
Index: sys/pool.h
===================================================================
RCS file: /cvs/src/sys/sys/pool.h,v
retrieving revision 1.53
diff -u -p -r1.53 pool.h
--- sys/pool.h 22 Sep 2014 01:04:58 -0000 1.53
+++ sys/pool.h 28 Oct 2014 03:05:50 -0000
@@ -128,8 +128,7 @@ struct pool {
RB_HEAD(phtree, pool_item_header)
pr_phtree;
- int pr_maxcolor; /* Cache colouring */
- int pr_curcolor;
+ u_int pr_maxcolors; /* Cache colouring */
int pr_phoffset; /* Offset in page of page header */
/*
