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[IA64] - Avoid slow TLB purges on SGI Altix systems 

flush_tlb_all() can be a scaling issue on large SGI Altix systems
since it uses the global call_lock and always executes on all cpus.
When a process enters flush_tlb_range() to purge TLBs for another
process, it is possible to avoid flush_tlb_all() and instead allow
sn2_global_tlb_purge() to purge TLBs only where necessary.

This patch modifies flush_tlb_range() so that this case can be handled
by platform TLB purge functions and updates ia64_global_tlb_purge()
accordingly.  sn2_global_tlb_purge() now calculates the region register
value from the mm argument introduced with this patch.

Signed-off-by: Dean Roe <roe@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Dean Roe 2005-10-27 15:41:04 -05:00 committed by Tony Luck
parent 72ab373a56
commit c1902aae32
3 changed files with 29 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
arch/ia64/mm/tlb.c
View File

@ -86,10 +86,15 @@ wrap_mmu_context (struct mm_struct *mm)
}
void
ia64_global_tlb_purge (unsigned long start, unsigned long end, unsigned long nbits)
ia64_global_tlb_purge (struct mm_struct *mm, unsigned long start, unsigned long end, unsigned long nbits)
{
static DEFINE_SPINLOCK(ptcg_lock);
if (mm != current->active_mm) {
flush_tlb_all();
return;
}
/* HW requires global serialization of ptc.ga. */
spin_lock(&ptcg_lock);
{
@ -135,15 +140,12 @@ flush_tlb_range (struct vm_area_struct *vma, unsigned long start, unsigned long
unsigned long size = end - start;
unsigned long nbits;
#ifndef CONFIG_SMP
if (mm != current->active_mm) {
/* this does happen, but perhaps it's not worth optimizing for? */
#ifdef CONFIG_SMP
flush_tlb_all();
#else
mm->context = 0;
#endif
return;
}
#endif
nbits = ia64_fls(size + 0xfff);
while (unlikely (((1UL << nbits) & purge.mask) == 0) && (nbits < purge.max_bits))
@ -153,7 +155,7 @@ flush_tlb_range (struct vm_area_struct *vma, unsigned long start, unsigned long
start &= ~((1UL << nbits) - 1);
# ifdef CONFIG_SMP
platform_global_tlb_purge(start, end, nbits);
platform_global_tlb_purge(mm, start, end, nbits);
# else
do {
ia64_ptcl(start, (nbits<<2));

31
arch/ia64/sn/kernel/sn2/sn2_smp.c
View File

@ -177,6 +177,7 @@ void sn_tlb_migrate_finish(struct mm_struct *mm)
/**
* sn2_global_tlb_purge - globally purge translation cache of virtual address range
* @mm: mm_struct containing virtual address range
* @start: start of virtual address range
* @end: end of virtual address range
* @nbits: specifies number of bytes to purge per instruction (num = 1<<(nbits & 0xfc))
@ -188,21 +189,22 @@ void sn_tlb_migrate_finish(struct mm_struct *mm)
* - cpu_vm_mask is a bit mask that indicates which cpus have loaded the context.
* - cpu_vm_mask is converted into a nodemask of the nodes containing the
* cpus in cpu_vm_mask.
* - if only one bit is set in cpu_vm_mask & it is the current cpu,
* then only the local TLB needs to be flushed. This flushing can be done
* using ptc.l. This is the common case & avoids the global spinlock.
* - if only one bit is set in cpu_vm_mask & it is the current cpu & the
* process is purging its own virtual address range, then only the
* local TLB needs to be flushed. This flushing can be done using
* ptc.l. This is the common case & avoids the global spinlock.
* - if multiple cpus have loaded the context, then flushing has to be
* done with ptc.g/MMRs under protection of the global ptc_lock.
*/
void
sn2_global_tlb_purge(unsigned long start, unsigned long end,
unsigned long nbits)
sn2_global_tlb_purge(struct mm_struct *mm, unsigned long start,
unsigned long end, unsigned long nbits)
{
int i, opt, shub1, cnode, mynasid, cpu, lcpu = 0, nasid, flushed = 0;
int mymm = (mm == current->active_mm);
volatile unsigned long *ptc0, *ptc1;
unsigned long itc, itc2, flags, data0 = 0, data1 = 0;
struct mm_struct *mm = current->active_mm;
unsigned long itc, itc2, flags, data0 = 0, data1 = 0, rr_value;
short nasids[MAX_NUMNODES], nix;
nodemask_t nodes_flushed;
@ -216,9 +218,12 @@ sn2_global_tlb_purge(unsigned long start, unsigned long end,
i++;
}
if (i == 0)
return;
preempt_disable();
if (likely(i == 1 && lcpu == smp_processor_id())) {
if (likely(i == 1 && lcpu == smp_processor_id() && mymm)) {
do {
ia64_ptcl(start, nbits << 2);
start += (1UL << nbits);
@ -229,7 +234,7 @@ sn2_global_tlb_purge(unsigned long start, unsigned long end,
return;
}
if (atomic_read(&mm->mm_users) == 1) {
if (atomic_read(&mm->mm_users) == 1 && mymm) {
flush_tlb_mm(mm);
__get_cpu_var(ptcstats).change_rid++;
preempt_enable();
@ -241,11 +246,13 @@ sn2_global_tlb_purge(unsigned long start, unsigned long end,
for_each_node_mask(cnode, nodes_flushed)
nasids[nix++] = cnodeid_to_nasid(cnode);
rr_value = (mm->context << 3) | REGION_NUMBER(start);
shub1 = is_shub1();
if (shub1) {
data0 = (1UL << SH1_PTC_0_A_SHFT) |
(nbits << SH1_PTC_0_PS_SHFT) |
((ia64_get_rr(start) >> 8) << SH1_PTC_0_RID_SHFT) |
(rr_value << SH1_PTC_0_RID_SHFT) |
(1UL << SH1_PTC_0_START_SHFT);
ptc0 = (long *)GLOBAL_MMR_PHYS_ADDR(0, SH1_PTC_0);
ptc1 = (long *)GLOBAL_MMR_PHYS_ADDR(0, SH1_PTC_1);
@ -254,7 +261,7 @@ sn2_global_tlb_purge(unsigned long start, unsigned long end,
(nbits << SH2_PTC_PS_SHFT) |
(1UL << SH2_PTC_START_SHFT);
ptc0 = (long *)GLOBAL_MMR_PHYS_ADDR(0, SH2_PTC +
((ia64_get_rr(start) >> 8) << SH2_PTC_RID_SHFT) );
(rr_value << SH2_PTC_RID_SHFT));
ptc1 = NULL;
}
@ -275,7 +282,7 @@ sn2_global_tlb_purge(unsigned long start, unsigned long end,
data0 = (data0 & ~SH2_PTC_ADDR_MASK) | (start & SH2_PTC_ADDR_MASK);
for (i = 0; i < nix; i++) {
nasid = nasids[i];
if ((!(sn2_ptctest & 3)) && unlikely(nasid == mynasid)) {
if ((!(sn2_ptctest & 3)) && unlikely(nasid == mynasid && mymm)) {
ia64_ptcga(start, nbits << 2);
ia64_srlz_i();
} else {

2
include/asm-ia64/machvec.h
View File

@ -26,7 +26,7 @@ typedef void ia64_mv_cpu_init_t (void);
typedef void ia64_mv_irq_init_t (void);
typedef void ia64_mv_send_ipi_t (int, int, int, int);
typedef void ia64_mv_timer_interrupt_t (int, void *, struct pt_regs *);
typedef void ia64_mv_global_tlb_purge_t (unsigned long, unsigned long, unsigned long);
typedef void ia64_mv_global_tlb_purge_t (struct mm_struct *, unsigned long, unsigned long, unsigned long);
typedef void ia64_mv_tlb_migrate_finish_t (struct mm_struct *);
typedef unsigned int ia64_mv_local_vector_to_irq (u8);
typedef char *ia64_mv_pci_get_legacy_mem_t (struct pci_bus *);