Re: [PATCH] - Reduce TLB flushing during process migration
From: Jack Steiner
Date: Fri Jul 02 2004 - 12:41:20 EST
On Fri, Jun 25, 2004 at 10:10:02PM -0700, David Mosberger wrote:
> >>>>> On Wed, 23 Jun 2004 14:33:18 -0700, Andrew Morton <akpm@xxxxxxxx> said:
>
> Andrew> Jack Steiner <steiner@xxxxxxx> wrote:
>
> >> This patch adds a platform specific hook to allow an arch-specific
> >> function to be called after an explicit migration.
>
> Andrew> OK by me. David, could you please merge this up?
>
> Andrew> Jack, please prepare an update for Documentation/cachetlb.txt.
>
> Jack, could you send me an updated patch which has all the revisions requested?
> Also, my preference would be for tlb_migrate_finish() to be a true no-op
> (not a call to a no-op function) when compiling for a platform that
> doesn't need this hook. Could you look into this?
>
> Thanks,
>
> --david
Here is the final patch. It should have all the requested changes.
For platforms that dont define their own tlb_migrate_finish, it is defined as :
#define tlb_migrate_finish(mm) do {} while (0)
I'm not sure if I understood your point above. This is consistent with
other noop definitions (at least some of them) & should not generate any
code.
Signed-off-by: Jack Steiner <steiner@xxxxxxx>
diff -uprN linux_base/arch/ia64/kernel/machvec.c linux/arch/ia64/kernel/machvec.c
--- linux_base/arch/ia64/kernel/machvec.c 2004-07-02 12:28:17.000000000 -0500
+++ linux/arch/ia64/kernel/machvec.c 2004-07-02 12:31:01.000000000 -0500
@@ -62,6 +62,12 @@ machvec_timer_interrupt (int irq, void *
EXPORT_SYMBOL(machvec_timer_interrupt);
void
+machvec_tlb_migrate_finish (struct mm_struct *mm)
+{
+}
+EXPORT_SYMBOL(machvec_tlb_migrate_finish);
+
+void
machvec_dma_sync_single (struct device *hwdev, dma_addr_t dma_handle, size_t size, int dir)
{
mb();
diff -uprN linux_base/arch/ia64/sn/kernel/sn2/sn2_smp.c linux/arch/ia64/sn/kernel/sn2/sn2_smp.c
--- linux_base/arch/ia64/sn/kernel/sn2/sn2_smp.c 2004-07-02 12:28:17.000000000 -0500
+++ linux/arch/ia64/sn/kernel/sn2/sn2_smp.c 2004-07-02 12:31:01.000000000 -0500
@@ -27,6 +27,7 @@
#include <asm/delay.h>
#include <asm/io.h>
#include <asm/smp.h>
+#include <asm/tlb.h>
#include <asm/numa.h>
#include <asm/bitops.h>
#include <asm/hw_irq.h>
@@ -60,6 +61,13 @@ wait_piowc(void)
}
+void
+sn_tlb_migrate_finish(struct mm_struct *mm)
+{
+ if (mm == current->mm)
+ flush_tlb_mm(mm);
+}
+
/**
* sn2_global_tlb_purge - globally purge translation cache of virtual address range
@@ -114,6 +122,13 @@ sn2_global_tlb_purge (unsigned long star
return;
}
+ if (atomic_read(&mm->mm_users) == 1) {
+ flush_tlb_mm(mm);
+ preempt_enable();
+ return;
+ }
+
+
nix = 0;
for (cnode=find_first_bit(&nodes_flushed, NR_NODES); cnode < NR_NODES;
cnode=find_next_bit(&nodes_flushed, NR_NODES, ++cnode))
diff -uprN linux_base/Documentation/cachetlb.txt linux/Documentation/cachetlb.txt
--- linux_base/Documentation/cachetlb.txt 2004-07-02 12:28:16.000000000 -0500
+++ linux/Documentation/cachetlb.txt 2004-07-02 12:31:01.000000000 -0500
@@ -132,6 +132,17 @@ changes occur:
translations for software managed TLB configurations.
The sparc64 port currently does this.
+7) void tlb_migrate_finish(struct mm_struct *mm)
+
+ This interface is called at the end of an explicit
+ process migration. This interface provides a hook
+ to allow a platform to update TLB or context-specific
+ information for the address space.
+
+ The ia64 sn2 platform is one example of a platform
+ that uses this interface.
+
+
Next, we have the cache flushing interfaces. In general, when Linux
is changing an existing virtual-->physical mapping to a new value,
the sequence will be in one of the following forms:
diff -uprN linux_base/include/asm-generic/tlb.h linux/include/asm-generic/tlb.h
--- linux_base/include/asm-generic/tlb.h 2004-07-02 12:28:23.000000000 -0500
+++ linux/include/asm-generic/tlb.h 2004-07-02 12:31:01.000000000 -0500
@@ -146,4 +146,6 @@ static inline void tlb_remove_page(struc
__pmd_free_tlb(tlb, pmdp); \
} while (0)
+#define tlb_migrate_finish(mm) do {} while (0)
+
#endif /* _ASM_GENERIC__TLB_H */
diff -uprN linux_base/include/asm-ia64/machvec.h linux/include/asm-ia64/machvec.h
--- linux_base/include/asm-ia64/machvec.h 2004-07-02 12:28:24.000000000 -0500
+++ linux/include/asm-ia64/machvec.h 2004-07-02 12:31:01.000000000 -0500
@@ -19,6 +19,7 @@ struct pt_regs;
struct scatterlist;
struct irq_desc;
struct page;
+struct mm_struct;
typedef void ia64_mv_setup_t (char **);
typedef void ia64_mv_cpu_init_t (void);
@@ -26,6 +27,7 @@ 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_tlb_migrate_finish_t (struct mm_struct *);
typedef struct irq_desc *ia64_mv_irq_desc (unsigned int);
typedef u8 ia64_mv_irq_to_vector (u8);
typedef unsigned int ia64_mv_local_vector_to_irq (u8 vector);
@@ -72,6 +74,7 @@ typedef unsigned long ia64_mv_readq_rela
extern void machvec_noop (void);
extern void machvec_setup (char **);
extern void machvec_timer_interrupt (int, void *, struct pt_regs *);
+extern void machvec_tlb_migrate_finish (struct mm_struct *);
extern void machvec_dma_sync_single (struct device *, dma_addr_t, size_t, int);
extern void machvec_dma_sync_sg (struct device *, struct scatterlist *, int, int);
@@ -95,6 +98,7 @@ extern void machvec_dma_sync_sg (struct
# define platform_send_ipi ia64_mv.send_ipi
# define platform_timer_interrupt ia64_mv.timer_interrupt
# define platform_global_tlb_purge ia64_mv.global_tlb_purge
+# define platform_tlb_migrate_finish ia64_mv.tlb_migrate_finish
# define platform_dma_init ia64_mv.dma_init
# define platform_dma_alloc_coherent ia64_mv.dma_alloc_coherent
# define platform_dma_free_coherent ia64_mv.dma_free_coherent
@@ -140,6 +144,7 @@ struct ia64_machine_vector {
ia64_mv_send_ipi_t *send_ipi;
ia64_mv_timer_interrupt_t *timer_interrupt;
ia64_mv_global_tlb_purge_t *global_tlb_purge;
+ ia64_mv_tlb_migrate_finish_t *tlb_migrate_finish;
ia64_mv_dma_init *dma_init;
ia64_mv_dma_alloc_coherent *dma_alloc_coherent;
ia64_mv_dma_free_coherent *dma_free_coherent;
@@ -181,6 +186,7 @@ struct ia64_machine_vector {
platform_send_ipi, \
platform_timer_interrupt, \
platform_global_tlb_purge, \
+ platform_tlb_migrate_finish, \
platform_dma_init, \
platform_dma_alloc_coherent, \
platform_dma_free_coherent, \
@@ -260,6 +266,9 @@ extern ia64_mv_dma_supported swiotlb_dm
#ifndef platform_global_tlb_purge
# define platform_global_tlb_purge ia64_global_tlb_purge /* default to architected version */
#endif
+#ifndef platform_tlb_migrate_finish
+# define platform_tlb_migrate_finish machvec_tlb_migrate_finish
+#endif
#ifndef platform_dma_init
# define platform_dma_init swiotlb_init
#endif
diff -uprN linux_base/include/asm-ia64/machvec_sn2.h linux/include/asm-ia64/machvec_sn2.h
--- linux_base/include/asm-ia64/machvec_sn2.h 2004-07-02 12:28:24.000000000 -0500
+++ linux/include/asm-ia64/machvec_sn2.h 2004-07-02 12:31:01.000000000 -0500
@@ -39,6 +39,7 @@ extern ia64_mv_irq_init_t sn_irq_init;
extern ia64_mv_send_ipi_t sn2_send_IPI;
extern ia64_mv_timer_interrupt_t sn_timer_interrupt;
extern ia64_mv_global_tlb_purge_t sn2_global_tlb_purge;
+extern ia64_mv_tlb_migrate_finish_t sn_tlb_migrate_finish;
extern ia64_mv_irq_desc sn_irq_desc;
extern ia64_mv_irq_to_vector sn_irq_to_vector;
extern ia64_mv_local_vector_to_irq sn_local_vector_to_irq;
@@ -83,6 +84,7 @@ extern ia64_mv_dma_supported sn_dma_sup
#define platform_send_ipi sn2_send_IPI
#define platform_timer_interrupt sn_timer_interrupt
#define platform_global_tlb_purge sn2_global_tlb_purge
+#define platform_tlb_migrate_finish sn_tlb_migrate_finish
#define platform_pci_fixup sn_pci_fixup
#define platform_inb __sn_inb
#define platform_inw __sn_inw
diff -uprN linux_base/include/asm-ia64/tlb.h linux/include/asm-ia64/tlb.h
--- linux_base/include/asm-ia64/tlb.h 2004-07-02 12:28:24.000000000 -0500
+++ linux/include/asm-ia64/tlb.h 2004-07-02 12:31:01.000000000 -0500
@@ -44,6 +44,7 @@
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/tlbflush.h>
+#include <asm/machvec.h>
#ifdef CONFIG_SMP
# define FREE_PTE_NR 2048
@@ -211,6 +212,8 @@ __tlb_remove_tlb_entry (struct mmu_gathe
tlb->end_addr = address + PAGE_SIZE;
}
+#define tlb_migrate_finish(mm) platform_tlb_migrate_finish(mm)
+
#define tlb_start_vma(tlb, vma) do { } while (0)
#define tlb_end_vma(tlb, vma) do { } while (0)
diff -uprN linux_base/kernel/sched.c linux/kernel/sched.c
--- linux_base/kernel/sched.c 2004-07-02 12:28:27.000000000 -0500
+++ linux/kernel/sched.c 2004-07-02 12:31:01.000000000 -0500
@@ -40,6 +40,7 @@
#include <linux/cpu.h>
#include <linux/percpu.h>
#include <linux/kthread.h>
+#include <asm/tlb.h>
#include <asm/unistd.h>
@@ -3335,6 +3336,7 @@ int set_cpus_allowed(task_t *p, cpumask_
task_rq_unlock(rq, &flags);
wake_up_process(rq->migration_thread);
wait_for_completion(&req.done);
+ tlb_migrate_finish(p->mm);
return 0;
}
out:
--
Thanks
Jack Steiner (steiner@xxxxxxx) 651-683-5302
Principal Engineer SGI - Silicon Graphics, Inc.
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