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[IA64] __per_cpu_idtrs[] is a memory hog
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__per_cpu_idtrs is statically allocated ... on CONFIG_NR_CPUS=4096
systems it hogs 16MB of memory. This is way too much for a quite
probably unused facility (only KVM uses dynamic TR registers).

Change to an array of pointers, and allocate entries as needed on
a per cpu basis.  Change the name too as the __per_cpu_ prefix is
confusing (this isn't a classic <linux/percpu.h> type object).

Signed-off-by: Tony Luck <tony.luck@intel.com>
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Tony Luck committed Jan 8, 2010
1 parent 410dc0a commit 6c57a33
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Showing 3 changed files with 24 additions and 15 deletions.
2 changes: 1 addition & 1 deletion arch/ia64/include/asm/tlb.h
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Original file line number Diff line number Diff line change
Expand Up @@ -74,7 +74,7 @@ struct ia64_tr_entry {
extern int ia64_itr_entry(u64 target_mask, u64 va, u64 pte, u64 log_size);
extern void ia64_ptr_entry(u64 target_mask, int slot);

extern struct ia64_tr_entry __per_cpu_idtrs[NR_CPUS][2][IA64_TR_ALLOC_MAX];
extern struct ia64_tr_entry *ia64_idtrs[NR_CPUS];

/*
region register macros
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5 changes: 4 additions & 1 deletion arch/ia64/kernel/mca.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1225,9 +1225,12 @@ static void mca_insert_tr(u64 iord)
unsigned long psr;
int cpu = smp_processor_id();

if (!ia64_idtrs[cpu])
return;

psr = ia64_clear_ic();
for (i = IA64_TR_ALLOC_BASE; i < IA64_TR_ALLOC_MAX; i++) {
p = &__per_cpu_idtrs[cpu][iord-1][i];
p = ia64_idtrs[cpu] + (iord - 1) * IA64_TR_ALLOC_MAX;
if (p->pte & 0x1) {
old_rr = ia64_get_rr(p->ifa);
if (old_rr != p->rr) {
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32 changes: 19 additions & 13 deletions arch/ia64/mm/tlb.c
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Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,7 @@ DEFINE_PER_CPU(u8, ia64_need_tlb_flush);
DEFINE_PER_CPU(u8, ia64_tr_num); /*Number of TR slots in current processor*/
DEFINE_PER_CPU(u8, ia64_tr_used); /*Max Slot number used by kernel*/

struct ia64_tr_entry __per_cpu_idtrs[NR_CPUS][2][IA64_TR_ALLOC_MAX];
struct ia64_tr_entry *ia64_idtrs[NR_CPUS];

/*
* Initializes the ia64_ctx.bitmap array based on max_ctx+1.
Expand Down Expand Up @@ -429,10 +429,16 @@ int ia64_itr_entry(u64 target_mask, u64 va, u64 pte, u64 log_size)
struct ia64_tr_entry *p;
int cpu = smp_processor_id();

if (!ia64_idtrs[cpu]) {
ia64_idtrs[cpu] = kmalloc(2 * IA64_TR_ALLOC_MAX *
sizeof (struct ia64_tr_entry), GFP_KERNEL);
if (!ia64_idtrs[cpu])
return -ENOMEM;
}
r = -EINVAL;
/*Check overlap with existing TR entries*/
if (target_mask & 0x1) {
p = &__per_cpu_idtrs[cpu][0][0];
p = ia64_idtrs[cpu];
for (i = IA64_TR_ALLOC_BASE; i <= per_cpu(ia64_tr_used, cpu);
i++, p++) {
if (p->pte & 0x1)
Expand All @@ -444,7 +450,7 @@ int ia64_itr_entry(u64 target_mask, u64 va, u64 pte, u64 log_size)
}
}
if (target_mask & 0x2) {
p = &__per_cpu_idtrs[cpu][1][0];
p = ia64_idtrs[cpu] + IA64_TR_ALLOC_MAX;
for (i = IA64_TR_ALLOC_BASE; i <= per_cpu(ia64_tr_used, cpu);
i++, p++) {
if (p->pte & 0x1)
Expand All @@ -459,16 +465,16 @@ int ia64_itr_entry(u64 target_mask, u64 va, u64 pte, u64 log_size)
for (i = IA64_TR_ALLOC_BASE; i < per_cpu(ia64_tr_num, cpu); i++) {
switch (target_mask & 0x3) {
case 1:
if (!(__per_cpu_idtrs[cpu][0][i].pte & 0x1))
if (!((ia64_idtrs[cpu] + i)->pte & 0x1))
goto found;
continue;
case 2:
if (!(__per_cpu_idtrs[cpu][1][i].pte & 0x1))
if (!((ia64_idtrs[cpu] + IA64_TR_ALLOC_MAX + i)->pte & 0x1))
goto found;
continue;
case 3:
if (!(__per_cpu_idtrs[cpu][0][i].pte & 0x1) &&
!(__per_cpu_idtrs[cpu][1][i].pte & 0x1))
if (!((ia64_idtrs[cpu] + i)->pte & 0x1) &&
!((ia64_idtrs[cpu] + IA64_TR_ALLOC_MAX + i)->pte & 0x1))
goto found;
continue;
default:
Expand All @@ -488,7 +494,7 @@ int ia64_itr_entry(u64 target_mask, u64 va, u64 pte, u64 log_size)
if (target_mask & 0x1) {
ia64_itr(0x1, i, va, pte, log_size);
ia64_srlz_i();
p = &__per_cpu_idtrs[cpu][0][i];
p = ia64_idtrs[cpu] + i;
p->ifa = va;
p->pte = pte;
p->itir = log_size << 2;
Expand All @@ -497,7 +503,7 @@ int ia64_itr_entry(u64 target_mask, u64 va, u64 pte, u64 log_size)
if (target_mask & 0x2) {
ia64_itr(0x2, i, va, pte, log_size);
ia64_srlz_i();
p = &__per_cpu_idtrs[cpu][1][i];
p = ia64_idtrs[cpu] + IA64_TR_ALLOC_MAX + i;
p->ifa = va;
p->pte = pte;
p->itir = log_size << 2;
Expand Down Expand Up @@ -528,7 +534,7 @@ void ia64_ptr_entry(u64 target_mask, int slot)
return;

if (target_mask & 0x1) {
p = &__per_cpu_idtrs[cpu][0][slot];
p = ia64_idtrs[cpu] + slot;
if ((p->pte&0x1) && is_tr_overlap(p, p->ifa, p->itir>>2)) {
p->pte = 0;
ia64_ptr(0x1, p->ifa, p->itir>>2);
Expand All @@ -537,7 +543,7 @@ void ia64_ptr_entry(u64 target_mask, int slot)
}

if (target_mask & 0x2) {
p = &__per_cpu_idtrs[cpu][1][slot];
p = ia64_idtrs[cpu] + IA64_TR_ALLOC_MAX + slot;
if ((p->pte & 0x1) && is_tr_overlap(p, p->ifa, p->itir>>2)) {
p->pte = 0;
ia64_ptr(0x2, p->ifa, p->itir>>2);
Expand All @@ -546,8 +552,8 @@ void ia64_ptr_entry(u64 target_mask, int slot)
}

for (i = per_cpu(ia64_tr_used, cpu); i >= IA64_TR_ALLOC_BASE; i--) {
if ((__per_cpu_idtrs[cpu][0][i].pte & 0x1) ||
(__per_cpu_idtrs[cpu][1][i].pte & 0x1))
if (((ia64_idtrs[cpu] + i)->pte & 0x1) ||
((ia64_idtrs[cpu] + IA64_TR_ALLOC_MAX + i)->pte & 0x1))
break;
}
per_cpu(ia64_tr_used, cpu) = i;
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