Stuart Henderson wrote:
> On 2016/03/09 20:49, Stefan Kempf wrote:
> > Here's a diff that allocates the most commonly used amap slot sizes
> > (between 1 and 16) using pool_get(9) instead of malloc(9). That should
> > reduce the pressure on kernel virtual address space somewhat (on amd64
> > at least),
>
> Thanks for the useful information and diff.
>
> I'm running a full ports build on i386 now with this in the kernel,
> and will run some more of my memory-hungry jobs on amd64 tomorrow.
I looked at the diff again and unfortunately there is a bug in the
first version. slotalloc was computed incorrectly in amap_extend()
when using pool(9).
That code path seems to not be executed often though
and can only be triggered with certain allocation sizes (maybe the
i386 ports build survives even with the first diff).
But please try the one below on amd64 if possible.
Index: uvm/uvm_amap.c
===================================================================
RCS file: /cvs/src/sys/uvm/uvm_amap.c,v
retrieving revision 1.60
diff -u -p -r1.60 uvm_amap.c
--- uvm/uvm_amap.c 6 Mar 2016 14:47:07 -0000 1.60
+++ uvm/uvm_amap.c 10 Mar 2016 05:19:09 -0000
@@ -52,8 +52,13 @@
struct pool uvm_amap_pool;
+/* Pools for amap slots for the most common amap slot sizes */
+struct pool uvm_amap_slot_pools[UVM_AMAP_CHUNK];
+
LIST_HEAD(, vm_amap) amap_list;
+static char amap_slot_pool_names[UVM_AMAP_CHUNK][13];
+
#define MALLOC_SLOT_UNIT (2 * sizeof(int) + sizeof(struct vm_anon *))
/*
@@ -151,10 +156,20 @@ pp_setreflen(int *ppref, int offset, int
void
amap_init(void)
{
+ int i;
+
/* Initialize the vm_amap pool. */
pool_init(&uvm_amap_pool, sizeof(struct vm_amap), 0, 0, PR_WAITOK,
"amappl", NULL);
pool_sethiwat(&uvm_amap_pool, 4096);
+
+ for (i = 0; i < nitems(uvm_amap_slot_pools); i++) {
+ snprintf(amap_slot_pool_names[i],
+ sizeof(amap_slot_pool_names[0]), "amapslotpl%d", i + 1);
+ pool_init(&uvm_amap_slot_pools[i], (i + 1) * MALLOC_SLOT_UNIT,
+ 0, 0, PR_WAITOK, amap_slot_pool_names[i], NULL);
+ pool_sethiwat(&uvm_amap_slot_pools[i], 4096);
+ }
}
/*
@@ -172,8 +187,13 @@ amap_alloc1(int slots, int padslots, int
if (amap == NULL)
return(NULL);
- totalslots = malloc_roundup((slots + padslots) * MALLOC_SLOT_UNIT) /
- MALLOC_SLOT_UNIT;
+ totalslots = slots + padslots;
+ KASSERT(totalslots > 0);
+
+ if (totalslots > UVM_AMAP_CHUNK)
+ totalslots = malloc_roundup(
+ (slots + padslots) * MALLOC_SLOT_UNIT) / MALLOC_SLOT_UNIT;
+
amap->am_ref = 1;
amap->am_flags = 0;
#ifdef UVM_AMAP_PPREF
@@ -183,8 +203,14 @@ amap_alloc1(int slots, int padslots, int
amap->am_nslot = slots;
amap->am_nused = 0;
- amap->am_slots = malloc(totalslots * MALLOC_SLOT_UNIT, M_UVMAMAP,
- waitf);
+ if (totalslots > UVM_AMAP_CHUNK)
+ amap->am_slots = malloc(totalslots * MALLOC_SLOT_UNIT,
+ M_UVMAMAP, waitf);
+ else
+ amap->am_slots = pool_get(
+ &uvm_amap_slot_pools[totalslots - 1],
+ (waitf == M_WAITOK) ? PR_WAITOK : PR_NOWAIT);
+
if (amap->am_slots == NULL)
goto fail1;
@@ -238,7 +264,12 @@ amap_free(struct vm_amap *amap)
KASSERT(amap->am_ref == 0 && amap->am_nused == 0);
KASSERT((amap->am_flags & AMAP_SWAPOFF) == 0);
- free(amap->am_slots, M_UVMAMAP, 0);
+ if (amap->am_maxslot > UVM_AMAP_CHUNK)
+ free(amap->am_slots, M_UVMAMAP, 0);
+ else
+ pool_put(&uvm_amap_slot_pools[amap->am_maxslot - 1],
+ amap->am_slots);
+
#ifdef UVM_AMAP_PPREF
if (amap->am_ppref && amap->am_ppref != PPREF_NONE)
free(amap->am_ppref, M_UVMAMAP, 0);
@@ -324,8 +355,7 @@ amap_extend(struct vm_map_entry *entry,
if (slotneed >= UVM_AMAP_LARGE)
return E2BIG;
- slotalloc = malloc_roundup(slotneed * MALLOC_SLOT_UNIT) /
- MALLOC_SLOT_UNIT;
+ slotalloc = slotneed;
#ifdef UVM_AMAP_PPREF
newppref = NULL;
if (amap->am_ppref && amap->am_ppref != PPREF_NONE) {
@@ -338,8 +368,14 @@ amap_extend(struct vm_map_entry *entry,
}
}
#endif
- newsl = malloc(slotalloc * MALLOC_SLOT_UNIT, M_UVMAMAP,
- M_WAITOK | M_CANFAIL);
+ if (slotneed > UVM_AMAP_CHUNK) {
+ slotalloc = malloc_roundup(slotneed * MALLOC_SLOT_UNIT) /
+ MALLOC_SLOT_UNIT;
+ newsl = malloc(slotalloc * MALLOC_SLOT_UNIT, M_UVMAMAP,
+ M_WAITOK | M_CANFAIL);
+ } else
+ newsl = pool_get(&uvm_amap_slot_pools[slotneed - 1],
+ PR_WAITOK | PR_LIMITFAIL);
if (newsl == NULL) {
#ifdef UVM_AMAP_PPREF
if (newppref != NULL) {
@@ -389,12 +425,17 @@ amap_extend(struct vm_map_entry *entry,
}
#endif
- /* update master values */
+ /* free */
+ if (amap->am_maxslot > UVM_AMAP_CHUNK)
+ free(oldsl, M_UVMAMAP, 0);
+ else
+ pool_put(&uvm_amap_slot_pools[amap->am_maxslot - 1],
+ oldsl);
+
+ /* and update master values */
amap->am_nslot = slotneed;
amap->am_maxslot = slotalloc;
- /* and free */
- free(oldsl, M_UVMAMAP, 0);
#ifdef UVM_AMAP_PPREF
if (oldppref && oldppref != PPREF_NONE)
free(oldppref, M_UVMAMAP, 0);
