Stefan Kempf wrote:
> 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.
There's still at least one issue with the diff. Again in amap_extend().
The slotalloc computation was still off :-(
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 18:15:17 -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(totalslots * 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 +355,12 @@ amap_extend(struct vm_map_entry *entry,
if (slotneed >= UVM_AMAP_LARGE)
return E2BIG;
- slotalloc = malloc_roundup(slotneed * MALLOC_SLOT_UNIT) /
- MALLOC_SLOT_UNIT;
+ if (slotneed > UVM_AMAP_CHUNK)
+ slotalloc = malloc_roundup(slotneed * MALLOC_SLOT_UNIT) /
+ MALLOC_SLOT_UNIT;
+ else
+ slotalloc = slotneed;
+
#ifdef UVM_AMAP_PPREF
newppref = NULL;
if (amap->am_ppref && amap->am_ppref != PPREF_NONE) {
@@ -338,8 +373,12 @@ 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)
+ newsl = malloc(slotalloc * MALLOC_SLOT_UNIT, M_UVMAMAP,
+ M_WAITOK | M_CANFAIL);
+ else
+ newsl = pool_get(&uvm_amap_slot_pools[slotalloc - 1],
+ PR_WAITOK | PR_LIMITFAIL);
if (newsl == NULL) {
#ifdef UVM_AMAP_PPREF
if (newppref != NULL) {
@@ -389,12 +428,17 @@ 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);
