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Groups > linux.kernel > #1637097
| From | Andy Lutomirski <luto@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [RFC 06/10] x86/mm: Refactor flush_tlb_mm_range() to merge local and remote cases |
| Date | 2017-05-08 00:20 +0200 |
| Message-ID | <tECH0-3sL-5@gated-at.bofh.it> (permalink) |
| References | <tECxj-3oj-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
The local flush path is very similar to the remote flush path.
Merge them.
This is intended to make no difference to behavior whatsoever. It
removes some code and will make future changes to the flushing
mechanics simpler.
This patch does remove one small optimization: flush_tlb_mm_range()
now has an unconditional smp_mb() instead of using MOV to CR3 or
INVLPG as a full barrier when applicable. I think this is okay for
a few reasons. First, smp_mb() is quite cheap compared to the cost
of a TLB flush. Second, this rearrangement makes a bigger
optimization available: with some work on the SMP function call
code, we could do the local and remote flushes in parallel. Third,
I'm planning a rework of the TLB flush algorithm that will require
an atomic operation at the beginning of each flush, and that
operation will replace the smp_mb().
Cc: Rik van Riel <riel@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/include/asm/tlbflush.h | 1 -
arch/x86/mm/tlb.c | 113 +++++++++++++++++-----------------------
2 files changed, 48 insertions(+), 66 deletions(-)
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 6d236c1aff89..c600d2d4a501 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -225,7 +225,6 @@ static inline void __flush_tlb_one(unsigned long addr)
* ..but the i386 has somewhat limited tlb flushing capabilities,
* and page-granular flushes are available only on i486 and up.
*/
-
struct flush_tlb_info {
struct mm_struct *mm;
unsigned long start;
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 3143c9a180e5..12b8812e8926 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -216,22 +216,9 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
* write/read ordering problems.
*/
-/*
- * TLB flush funcation:
- * 1) Flush the tlb entries if the cpu uses the mm that's being flushed.
- * 2) Leave the mm if we are in the lazy tlb mode.
- */
-static void flush_tlb_func(void *info)
+static void flush_tlb_func_common(const struct flush_tlb_info *f,
+ bool local, enum tlb_flush_reason reason)
{
- const struct flush_tlb_info *f = info;
-
- inc_irq_stat(irq_tlb_count);
-
- if (f->mm && f->mm != this_cpu_read(cpu_tlbstate.active_mm))
- return;
-
- count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
-
if (this_cpu_read(cpu_tlbstate.state) != TLBSTATE_OK) {
leave_mm(smp_processor_id());
return;
@@ -239,7 +226,9 @@ static void flush_tlb_func(void *info)
if (f->end == TLB_FLUSH_ALL) {
local_flush_tlb();
- trace_tlb_flush(TLB_REMOTE_SHOOTDOWN, TLB_FLUSH_ALL);
+ if (local)
+ count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
+ trace_tlb_flush(reason, TLB_FLUSH_ALL);
} else {
unsigned long addr;
unsigned long nr_pages =
@@ -249,10 +238,32 @@ static void flush_tlb_func(void *info)
__flush_tlb_single(addr);
addr += PAGE_SIZE;
}
- trace_tlb_flush(TLB_REMOTE_SHOOTDOWN, nr_pages);
+ if (local)
+ count_vm_tlb_events(NR_TLB_LOCAL_FLUSH_ONE, nr_pages);
+ trace_tlb_flush(reason, nr_pages);
}
}
+static void flush_tlb_func_local(void *info, enum tlb_flush_reason reason)
+{
+ const struct flush_tlb_info *f = info;
+
+ flush_tlb_func_common(f, true, reason);
+}
+
+static void flush_tlb_func_remote(void *info)
+{
+ const struct flush_tlb_info *f = info;
+
+ inc_irq_stat(irq_tlb_count);
+
+ if (f->mm && f->mm != this_cpu_read(cpu_tlbstate.active_mm))
+ return;
+
+ count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
+ flush_tlb_func_common(f, false, TLB_REMOTE_SHOOTDOWN);
+}
+
void native_flush_tlb_others(const struct cpumask *cpumask,
const struct flush_tlb_info *info)
{
@@ -269,11 +280,11 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
cpu = smp_processor_id();
cpumask = uv_flush_tlb_others(cpumask, info);
if (cpumask)
- smp_call_function_many(cpumask, flush_tlb_func,
+ smp_call_function_many(cpumask, flush_tlb_func_remote,
(void *)info, 1);
return;
}
- smp_call_function_many(cpumask, flush_tlb_func,
+ smp_call_function_many(cpumask, flush_tlb_func_remote,
(void *)info, 1);
}
@@ -292,61 +303,33 @@ static unsigned long tlb_single_page_flush_ceiling __read_mostly = 33;
void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
unsigned long end, unsigned long vmflag)
{
- unsigned long addr;
- struct flush_tlb_info info;
- /* do a global flush by default */
- unsigned long base_pages_to_flush = TLB_FLUSH_ALL;
-
- preempt_disable();
+ int cpu;
- if ((end != TLB_FLUSH_ALL) && !(vmflag & VM_HUGETLB))
- base_pages_to_flush = (end - start) >> PAGE_SHIFT;
- if (base_pages_to_flush > tlb_single_page_flush_ceiling)
- base_pages_to_flush = TLB_FLUSH_ALL;
-
- if (current->active_mm != mm) {
- /* Synchronize with switch_mm. */
- smp_mb();
-
- goto out;
- }
-
- if (this_cpu_read(cpu_tlbstate.state) != TLBSTATE_OK) {
- leave_mm(smp_processor_id());
+ struct flush_tlb_info info = {
+ .mm = mm,
+ };
- /* Synchronize with switch_mm. */
- smp_mb();
+ cpu = get_cpu();
- goto out;
- }
+ /* Synchronize with switch_mm. */
+ smp_mb();
- /*
- * Both branches below are implicit full barriers (MOV to CR or
- * INVLPG) that synchronize with switch_mm.
- */
- if (base_pages_to_flush == TLB_FLUSH_ALL) {
- count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
- local_flush_tlb();
+ /* Should we flush just the requested range? */
+ if ((end != TLB_FLUSH_ALL) &&
+ !(vmflag & VM_HUGETLB) &&
+ ((end - start) >> PAGE_SHIFT) <= tlb_single_page_flush_ceiling) {
+ info.start = start;
+ info.end = end;
} else {
- /* flush range by one by one 'invlpg' */
- for (addr = start; addr < end; addr += PAGE_SIZE) {
- count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);
- __flush_tlb_single(addr);
- }
- }
- trace_tlb_flush(TLB_LOCAL_MM_SHOOTDOWN, base_pages_to_flush);
-out:
- info.mm = mm;
- if (base_pages_to_flush == TLB_FLUSH_ALL) {
info.start = 0UL;
info.end = TLB_FLUSH_ALL;
- } else {
- info.start = start;
- info.end = end;
}
- if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
+
+ if (mm == current->active_mm)
+ flush_tlb_func_local(&info, TLB_LOCAL_MM_SHOOTDOWN);
+ if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids)
flush_tlb_others(mm_cpumask(mm), &info);
- preempt_enable();
+ put_cpu();
}
--
2.9.3
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[RFC 00/10] x86 TLB flush cleanups, moving toward PCID support Andy Lutomirski <luto@kernel.org> - 2017-05-08 00:10 +0200
[RFC 03/10] x86/mm: Make the batched unmap TLB flush API more generic Andy Lutomirski <luto@kernel.org> - 2017-05-08 00:10 +0200
Re: [RFC 03/10] x86/mm: Make the batched unmap TLB flush API more generic Dave Hansen <dave.hansen@intel.com> - 2017-05-08 17:40 +0200
Re: [RFC 03/10] x86/mm: Make the batched unmap TLB flush API more generic Andy Lutomirski <luto@kernel.org> - 2017-05-09 15:10 +0200
Re: [RFC 03/10] x86/mm: Make the batched unmap TLB flush API more generic Mel Gorman <mgorman@suse.de> - 2017-05-09 16:50 +0200
Re: [RFC 03/10] x86/mm: Make the batched unmap TLB flush API more generic Dave Hansen <dave.hansen@intel.com> - 2017-05-09 19:20 +0200
Re: [RFC 03/10] x86/mm: Make the batched unmap TLB flush API more generic Andy Lutomirski <luto@kernel.org> - 2017-05-10 01:00 +0200
[RFC 07/10] x86/mm: Use new merged flush logic in arch_tlbbatch_flush() Andy Lutomirski <luto@kernel.org> - 2017-05-08 00:10 +0200
[RFC 04/10] x86/mm: Pass flush_tlb_info to flush_tlb_others() etc Andy Lutomirski <luto@kernel.org> - 2017-05-08 00:10 +0200
Re: [RFC 04/10] x86/mm: Pass flush_tlb_info to flush_tlb_others() etc Nadav Amit <nadav.amit@gmail.com> - 2017-05-11 22:10 +0200
[RFC 05/10] x86/mm: Change the leave_mm() condition for local TLB flushes Andy Lutomirski <luto@kernel.org> - 2017-05-08 00:10 +0200
[RFC 02/10] x86/mm: Reduce indentation in flush_tlb_func() Andy Lutomirski <luto@kernel.org> - 2017-05-08 00:10 +0200
[RFC 08/10] x86/mm: Remove the UP tlbflush code; always use the formerly SMP code Andy Lutomirski <luto@kernel.org> - 2017-05-08 00:10 +0200
[RFC 01/10] x86/mm: Reimplement flush_tlb_page() using flush_tlb_mm_range() Andy Lutomirski <luto@kernel.org> - 2017-05-08 00:10 +0200
Re: [RFC 01/10] x86/mm: Reimplement flush_tlb_page() using flush_tlb_mm_range() Borislav Petkov <bp@suse.de> - 2017-05-11 19:50 +0200
[RFC 10/10] x86,kvm: Teach KVM's VMX code that CR3 isn't a constant Andy Lutomirski <luto@kernel.org> - 2017-05-08 00:20 +0200
[RFC 06/10] x86/mm: Refactor flush_tlb_mm_range() to merge local and remote cases Andy Lutomirski <luto@kernel.org> - 2017-05-08 00:20 +0200
Re: [RFC 00/10] x86 TLB flush cleanups, moving toward PCID support Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-08 01:00 +0200
Re: [RFC 00/10] x86 TLB flush cleanups, moving toward PCID support Ingo Molnar <mingo@kernel.org> - 2017-05-08 01:50 +0200
Re: [RFC 00/10] x86 TLB flush cleanups, moving toward PCID support Nadav Amit <nadav.amit@gmail.com> - 2017-05-08 18:40 +0200
Re: [RFC 00/10] x86 TLB flush cleanups, moving toward PCID support Andy Lutomirski <luto@kernel.org> - 2017-05-09 14:50 +0200
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