[PATCH 1/2] powerpc: Add function to copy mm_context_t to the paca

Subsystems: linux for powerpc (32-bit and 64-bit), the rest

STALE3860d

8 messages, 3 authors, 2016-01-11 · open the first message on its own page

[PATCH 1/2] powerpc: Add function to copy mm_context_t to the paca

From: Michael Neuling <hidden>
Date: 2015-10-28 04:54:24

This adds a function to copy the mm->context to the paca.  This is
only a basic conversion for now but will be used more extensively in
the next patch.

This also adds #ifdef CONFIG_PPC_BOOK3S around this code since it's
not used elsewhere.

Signed-off-by: Michael Neuling <redacted>
---
 arch/powerpc/include/asm/paca.h   | 11 +++++++++++
 arch/powerpc/kernel/asm-offsets.c |  2 ++
 arch/powerpc/mm/hash_utils_64.c   |  5 +++--
 arch/powerpc/mm/slb.c             |  2 +-
 arch/powerpc/mm/slice.c           |  3 +--
 5 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 70bd438..1cc6e08 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h

@@ -131,7 +131,9 @@ struct paca_struct {
 	struct tlb_core_data tcd;
 #endif /* CONFIG_PPC_BOOK3E */
 
+#ifdef CONFIG_PPC_BOOK3S
 	mm_context_t context;
+#endif
 
 	/*
 	 * then miscellaneous read-write fields

@@ -194,6 +196,15 @@ struct paca_struct {
 #endif
 };
 
+#ifdef CONFIG_PPC_BOOK3S
+static inline void copy_mm_to_paca(mm_context_t *context)
+{
+	get_paca()->context = *context;
+}
+#else
+static inline void copy_mm_to_paca(mm_context_t *context){}
+#endif
+
 extern struct paca_struct *paca;
 extern void initialise_paca(struct paca_struct *new_paca, int cpu);
 extern void setup_paca(struct paca_struct *new_paca);

diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 221d584..9db7be2 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c

@@ -185,6 +185,7 @@ int main(void)
 	DEFINE(PACAKMSR, offsetof(struct paca_struct, kernel_msr));
 	DEFINE(PACASOFTIRQEN, offsetof(struct paca_struct, soft_enabled));
 	DEFINE(PACAIRQHAPPENED, offsetof(struct paca_struct, irq_happened));
+#ifdef CONFIG_PPC_BOOK3S
 	DEFINE(PACACONTEXTID, offsetof(struct paca_struct, context.id));
 #ifdef CONFIG_PPC_MM_SLICES
 	DEFINE(PACALOWSLICESPSIZE, offsetof(struct paca_struct,

@@ -193,6 +194,7 @@ int main(void)
 					    context.high_slices_psize));
 	DEFINE(MMUPSIZEDEFSIZE, sizeof(struct mmu_psize_def));
 #endif /* CONFIG_PPC_MM_SLICES */
+#endif
 
 #ifdef CONFIG_PPC_BOOK3E
 	DEFINE(PACAPGD, offsetof(struct paca_struct, pgd));

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index aee7017..fa62eb0 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c

@@ -906,7 +906,8 @@ void demote_segment_4k(struct mm_struct *mm, unsigned long addr)
 	slice_set_range_psize(mm, addr, 1, MMU_PAGE_4K);
 	copro_flush_all_slbs(mm);
 	if ((get_paca_psize(addr) != MMU_PAGE_4K) && (current->mm == mm)) {
-		get_paca()->context = mm->context;
+
+		copy_mm_to_paca(&mm->context);
 		slb_flush_and_rebolt();
 	}
 }

@@ -973,7 +974,7 @@ static void check_paca_psize(unsigned long ea, struct mm_struct *mm,
 {
 	if (user_region) {
 		if (psize != get_paca_psize(ea)) {
-			get_paca()->context = mm->context;
+			copy_mm_to_paca(&mm->context);
 			slb_flush_and_rebolt();
 		}
 	} else if (get_paca()->vmalloc_sllp !=

diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index 8a32a2be..4412b8e 100644
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c

@@ -223,7 +223,7 @@ void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
 		asm volatile("slbie %0" : : "r" (slbie_data));
 
 	get_paca()->slb_cache_ptr = 0;
-	get_paca()->context = mm->context;
+	copy_mm_to_paca(&mm->context);
 
 	/*
 	 * preload some userspace segments into the SLB.

diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index 0f432a7..42954f0 100644
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c

@@ -185,8 +185,7 @@ static void slice_flush_segments(void *parm)
 	if (mm != current->active_mm)
 		return;
 
-	/* update the paca copy of the context struct */
-	get_paca()->context = current->active_mm->context;
+	copy_mm_to_paca(&current->active_mm->context);
 
 	local_irq_save(flags);
 	slb_flush_and_rebolt();

-- 
2.5.0

[PATCH 2/2] powerpc: Copy only required pieces of the mm_context_t to the paca

From: Michael Neuling <hidden>
Date: 2015-10-28 04:54:25

Currently we copy the whole mm_context_t to the paca but only access a
few bits of it.  This is wasteful of space paca and also takes quite
some time in the hot path of context switching.

This patch pulls in only the required bits from the mm_context_t to
the paca and on context switch, copies only those.

Benchmarking this (On top of Anton's recent MSR context switching
changes [1]) using processes and yield shows an improvement of almost
3% on POWER8:

  http://ozlabs.org/~anton/junkcode/context_switch2.c
  ./context_switch2 --test=yield --process 0 0

1. https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-October/135700.html

Signed-off-by: Michael Neuling <redacted>
---
 arch/powerpc/include/asm/paca.h   | 17 +++++++++++++++--
 arch/powerpc/kernel/asm-offsets.c |  8 ++++----
 arch/powerpc/mm/hash_utils_64.c   |  4 ++--
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 1cc6e08..1c0d9f4 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h

@@ -132,7 +132,13 @@ struct paca_struct {
 #endif /* CONFIG_PPC_BOOK3E */
 
 #ifdef CONFIG_PPC_BOOK3S
-	mm_context_t context;
+	mm_context_id_t context_id;
+#ifdef CONFIG_PPC_MM_SLICES
+	u64 context_low_slices_psize;
+	unsigned char context_high_slices_psize[SLICE_ARRAY_SIZE];
+#else
+	u16 context_sllp;
+#endif
 #endif
 
 	/*

@@ -199,7 +205,14 @@ struct paca_struct {
 #ifdef CONFIG_PPC_BOOK3S
 static inline void copy_mm_to_paca(mm_context_t *context)
 {
-	get_paca()->context = *context;
+	get_paca()->context_id = context->id;
+#ifdef CONFIG_PPC_MM_SLICES
+	get_paca()->context_low_slices_psize = context->low_slices_psize;
+	memcpy(&get_paca()->context_high_slices_psize,
+	       &context->high_slices_psize, SLICE_ARRAY_SIZE);
+#else
+	get_paca()->context_sllp = context->sllp;
+#endif
 }
 #else
 static inline void copy_mm_to_paca(mm_context_t *context){}

diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 9db7be2..d5903a9 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c

@@ -186,12 +186,12 @@ int main(void)
 	DEFINE(PACASOFTIRQEN, offsetof(struct paca_struct, soft_enabled));
 	DEFINE(PACAIRQHAPPENED, offsetof(struct paca_struct, irq_happened));
 #ifdef CONFIG_PPC_BOOK3S
-	DEFINE(PACACONTEXTID, offsetof(struct paca_struct, context.id));
+	DEFINE(PACACONTEXTID, offsetof(struct paca_struct, context_id));
 #ifdef CONFIG_PPC_MM_SLICES
 	DEFINE(PACALOWSLICESPSIZE, offsetof(struct paca_struct,
-					    context.low_slices_psize));
+					    context_low_slices_psize));
 	DEFINE(PACAHIGHSLICEPSIZE, offsetof(struct paca_struct,
-					    context.high_slices_psize));
+					    context_high_slices_psize));
 	DEFINE(MMUPSIZEDEFSIZE, sizeof(struct mmu_psize_def));
 #endif /* CONFIG_PPC_MM_SLICES */
 #endif

@@ -224,7 +224,7 @@ int main(void)
 #ifdef CONFIG_PPC_MM_SLICES
 	DEFINE(MMUPSIZESLLP, offsetof(struct mmu_psize_def, sllp));
 #else
-	DEFINE(PACACONTEXTSLLP, offsetof(struct paca_struct, context.sllp));
+	DEFINE(PACACONTEXTSLLP, offsetof(struct paca_struct, context_sllp));
 #endif /* CONFIG_PPC_MM_SLICES */
 	DEFINE(PACA_EXGEN, offsetof(struct paca_struct, exgen));
 	DEFINE(PACA_EXMC, offsetof(struct paca_struct, exmc));

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index fa62eb0..0e087e4 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c

@@ -877,11 +877,11 @@ static unsigned int get_paca_psize(unsigned long addr)
 	unsigned long index, mask_index;
 
 	if (addr < SLICE_LOW_TOP) {
-		lpsizes = get_paca()->context.low_slices_psize;
+		lpsizes = get_paca()->context_low_slices_psize;
 		index = GET_LOW_SLICE_INDEX(addr);
 		return (lpsizes >> (index * 4)) & 0xF;
 	}
-	hpsizes = get_paca()->context.high_slices_psize;
+	hpsizes = get_paca()->context_high_slices_psize;
 	index = GET_HIGH_SLICE_INDEX(addr);
 	mask_index = index & 0x1;
 	return (hpsizes[index >> 1] >> (mask_index * 4)) & 0xF;

-- 
2.5.0

Re: [PATCH 2/2] powerpc: Copy only required pieces of the mm_context_t to the paca

From: Anton Blanchard <hidden>
Date: 2015-12-09 12:17:38

Currently we copy the whole mm_context_t to the paca but only access a
few bits of it.  This is wasteful of space paca and also takes quite
some time in the hot path of context switching.

This patch pulls in only the required bits from the mm_context_t to
the paca and on context switch, copies only those.

Benchmarking this (On top of Anton's recent MSR context switching
changes [1]) using processes and yield shows an improvement of almost
3% on POWER8:

  http://ozlabs.org/~anton/junkcode/context_switch2.c
  ./context_switch2 --test=yield --process 0 0

Now the context switch series is in, I tested this against powerpc-next
and still see a ~3% improvement.

Anton

quoted hunk

1.
https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-October/135700.html

Signed-off-by: Michael Neuling <redacted>
---
 arch/powerpc/include/asm/paca.h   | 17 +++++++++++++++--
 arch/powerpc/kernel/asm-offsets.c |  8 ++++----
 arch/powerpc/mm/hash_utils_64.c   |  4 ++--
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/paca.h

b/arch/powerpc/include/asm/paca.h index 1cc6e08..1c0d9f4 100644

--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h

@@ -132,7 +132,13 @@ struct paca_struct {
 #endif /* CONFIG_PPC_BOOK3E */
 
 #ifdef CONFIG_PPC_BOOK3S
-	mm_context_t context;
+	mm_context_id_t context_id;
+#ifdef CONFIG_PPC_MM_SLICES
+	u64 context_low_slices_psize;
+	unsigned char context_high_slices_psize[SLICE_ARRAY_SIZE];
+#else
+	u16 context_sllp;
+#endif
 #endif
 
 	/*

@@ -199,7 +205,14 @@ struct paca_struct {
 #ifdef CONFIG_PPC_BOOK3S
 static inline void copy_mm_to_paca(mm_context_t *context)
 {
-	get_paca()->context = *context;
+	get_paca()->context_id = context->id;
+#ifdef CONFIG_PPC_MM_SLICES
+	get_paca()->context_low_slices_psize =

context->low_slices_psize;
+	memcpy(&get_paca()->context_high_slices_psize,
+	       &context->high_slices_psize, SLICE_ARRAY_SIZE);
+#else
+	get_paca()->context_sllp = context->sllp;
+#endif
 }
 #else
 static inline void copy_mm_to_paca(mm_context_t *context){}

diff --git a/arch/powerpc/kernel/asm-offsets.c

b/arch/powerpc/kernel/asm-offsets.c index 9db7be2..d5903a9 100644

--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c

@@ -186,12 +186,12 @@ int main(void)
 	DEFINE(PACASOFTIRQEN, offsetof(struct paca_struct,

soft_enabled)); DEFINE(PACAIRQHAPPENED, offsetof(struct paca_struct,
irq_happened)); #ifdef CONFIG_PPC_BOOK3S
-	DEFINE(PACACONTEXTID, offsetof(struct paca_struct,
context.id));
+	DEFINE(PACACONTEXTID, offsetof(struct paca_struct,
context_id)); #ifdef CONFIG_PPC_MM_SLICES
 	DEFINE(PACALOWSLICESPSIZE, offsetof(struct paca_struct,
-
context.low_slices_psize));
+
context_low_slices_psize)); DEFINE(PACAHIGHSLICEPSIZE,
offsetof(struct paca_struct,
-
context.high_slices_psize));
+
context_high_slices_psize)); DEFINE(MMUPSIZEDEFSIZE, sizeof(struct
mmu_psize_def)); #endif /* CONFIG_PPC_MM_SLICES */
 #endif

@@ -224,7 +224,7 @@ int main(void)
 #ifdef CONFIG_PPC_MM_SLICES
 	DEFINE(MMUPSIZESLLP, offsetof(struct mmu_psize_def, sllp));
 #else
-	DEFINE(PACACONTEXTSLLP, offsetof(struct paca_struct,

context.sllp));
+	DEFINE(PACACONTEXTSLLP, offsetof(struct paca_struct,
context_sllp)); #endif /* CONFIG_PPC_MM_SLICES */
 	DEFINE(PACA_EXGEN, offsetof(struct paca_struct, exgen));
 	DEFINE(PACA_EXMC, offsetof(struct paca_struct, exmc));

diff --git a/arch/powerpc/mm/hash_utils_64.c

b/arch/powerpc/mm/hash_utils_64.c index fa62eb0..0e087e4 100644

--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c

@@ -877,11 +877,11 @@ static unsigned int get_paca_psize(unsigned

long addr) unsigned long index, mask_index;
 
 	if (addr < SLICE_LOW_TOP) {
-		lpsizes = get_paca()->context.low_slices_psize;
+		lpsizes = get_paca()->context_low_slices_psize;
 		index = GET_LOW_SLICE_INDEX(addr);
 		return (lpsizes >> (index * 4)) & 0xF;
 	}
-	hpsizes = get_paca()->context.high_slices_psize;
+	hpsizes = get_paca()->context_high_slices_psize;
 	index = GET_HIGH_SLICE_INDEX(addr);
 	mask_index = index & 0x1;
 	return (hpsizes[index >> 1] >> (mask_index * 4)) & 0xF;

[PATCH v2 2/2] powerpc: Copy only required pieces of the mm_context_t to the paca

From: Michael Neuling <hidden>
Date: 2015-12-10 03:46:51

Currently we copy the whole mm_context_t to the paca but only access a
few bits of it.  This is wasteful of space paca and also takes quite
some time in the hot path of context switching.

This patch pulls in only the required bits from the mm_context_t to
the paca and on context switch, copies only those.

Benchmarking this (On top of Anton's recent MSR context switching
changes [1]) using processes and yield shows an improvement of almost
3% on POWER8:

  http://ozlabs.org/~anton/junkcode/context_switch2.c
  ./context_switch2 --test=3Dyield --process 0 0

1. https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-October/135700.
html

Signed-off-by: Michael Neuling <redacted>
---
v2:
  Added missing include which broke allmodconfig (noticed by anton)

 include/asm/paca.h   |   18 ++++++++++++++++--
 kernel/asm-offsets.c |    8 ++++----
 mm/hash_utils_64.c   |    4 ++--
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/paca.h

b/arch/powerpc/include/asm/paca.h
index 1cc6e08..06cdaee 100644

--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h

@@ -16,6 +16,7 @@

=20
 #ifdef CONFIG_PPC64
=20
+#include <linux/string.h>
 #include <asm/types.h>
 #include <asm/lppaca.h>
 #include <asm/mmu.h>

@@ -132,7 +133,13 @@ struct paca_struct {
 #endif /* CONFIG_PPC_BOOK3E */

=20
 #ifdef CONFIG_PPC_BOOK3S
-	mm_context_t context;
+	mm_context_id_t context_id;
+#ifdef CONFIG_PPC_MM_SLICES
+	u64 context_low_slices_psize;
+	unsigned char context_high_slices_psize[SLICE_ARRAY_SIZE];
+#else
+	u16 context_sllp;
+#endif
 #endif
=20
 	/*

@@ -199,7 +206,14 @@ struct paca_struct {
 #ifdef CONFIG_PPC_BOOK3S
 static inline void copy_mm_to_paca(mm_context_t *context)
 {
-	get_paca()->context =3D *context;
+	get_paca()->context_id =3D context->id;
+#ifdef CONFIG_PPC_MM_SLICES
+	get_paca()->context_low_slices_psize =3D context
->low_slices_psize;
+	memcpy(&get_paca()->context_high_slices_psize,
+	       &context->high_slices_psize, SLICE_ARRAY_SIZE);
+#else
+	get_paca()->context_sllp =3D context->sllp;
+#endif
 }
 #else
 static inline void copy_mm_to_paca(mm_context_t *context){}

diff --git a/arch/powerpc/kernel/asm-offsets.c

b/arch/powerpc/kernel/asm-offsets.c
index 9db7be2..d5903a9 100644

--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c

@@ -186,12 +186,12 @@ int main(void)
 	DEFINE(PACASOFTIRQEN, offsetof(struct paca_struct,

soft_enabled));
 	DEFINE(PACAIRQHAPPENED, offsetof(struct paca_struct,
irq_happened));
 #ifdef CONFIG_PPC_BOOK3S
-	DEFINE(PACACONTEXTID, offsetof(struct paca_struct,
context.id));
+	DEFINE(PACACONTEXTID, offsetof(struct paca_struct,
context_id));
 #ifdef CONFIG_PPC_MM_SLICES
 	DEFINE(PACALOWSLICESPSIZE, offsetof(struct paca_struct,
-					  =20
 context.low_slices_psize));
+					  =20
 context_low_slices_psize));
 	DEFINE(PACAHIGHSLICEPSIZE, offsetof(struct paca_struct,
-					  =20
 context.high_slices_psize));
+					  =20
 context_high_slices_psize));
 	DEFINE(MMUPSIZEDEFSIZE, sizeof(struct mmu_psize_def));
 #endif /* CONFIG_PPC_MM_SLICES */
 #endif

@@ -224,7 +224,7 @@ int main(void)
 #ifdef CONFIG_PPC_MM_SLICES
 	DEFINE(MMUPSIZESLLP, offsetof(struct mmu_psize_def, sllp));
 #else
-	DEFINE(PACACONTEXTSLLP, offsetof(struct paca_struct,

context.sllp));
+	DEFINE(PACACONTEXTSLLP, offsetof(struct paca_struct,
context_sllp));
 #endif /* CONFIG_PPC_MM_SLICES */
 	DEFINE(PACA_EXGEN, offsetof(struct paca_struct, exgen));
 	DEFINE(PACA_EXMC, offsetof(struct paca_struct, exmc));

diff --git a/arch/powerpc/mm/hash_utils_64.c

b/arch/powerpc/mm/hash_utils_64.c
index 0aa526e..ae98d58 100644

--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c

@@ -877,11 +877,11 @@ static unsigned int get_paca_psize(unsigned long

addr)
 	unsigned long index, mask_index;
=20
 	if (addr < SLICE_LOW_TOP) {
-		lpsizes =3D get_paca()->context.low_slices_psize;
+		lpsizes =3D get_paca()->context_low_slices_psize;
 		index =3D GET_LOW_SLICE_INDEX(addr);
 		return (lpsizes >> (index * 4)) & 0xF;
 	}
-	hpsizes =3D get_paca()->context.high_slices_psize;
+	hpsizes =3D get_paca()->context_high_slices_psize;
 	index =3D GET_HIGH_SLICE_INDEX(addr);
 	mask_index =3D index & 0x1;
 	return (hpsizes[index >> 1] >> (mask_index * 4)) & 0xF;

Re: [PATCH v2 2/2] powerpc: Copy only required pieces of the mm_context_t to the paca

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2015-12-10 10:00:30

On Thu, 2015-12-10 at 14:46 +1100, Michael Neuling wrote:

quoted hunk

Currently we copy the whole mm_context_t to the paca but only access a
few bits of it.  This is wasteful of space paca and also takes quite
some time in the hot path of context switching.

diff --git a/arch/powerpc/include/asm/paca.h

b/arch/powerpc/include/asm/paca.h
index 1cc6e08..06cdaee 100644

--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h

@@ -199,7 +206,14 @@ struct paca_struct {
 #ifdef CONFIG_PPC_BOOK3S
 static inline void copy_mm_to_paca(mm_context_t *context)
 {
-	get_paca()->context = *context;
+	get_paca()->context_id = context->id;
+#ifdef CONFIG_PPC_MM_SLICES
+	get_paca()->context_low_slices_psize = context
->low_slices_psize;

Patch is wrapped ^

And so on.

cheers

[PATCH v3 2/2] powerpc: Copy only required pieces of the mm_context_t to the paca

From: Michael Neuling <hidden>
Date: 2015-12-10 22:34:42

Currently we copy the whole mm_context_t to the paca but only access a
few bits of it.  This is wasteful of space paca and also takes quite
some time in the hot path of context switching.

This patch pulls in only the required bits from the mm_context_t to
the paca and on context switch, copies only those.

Benchmarking this (On top of Anton's recent MSR context switching
changes [1]) using processes and yield shows an improvement of almost
3% on POWER8:

  http://ozlabs.org/~anton/junkcode/context_switch2.c
  ./context_switch2 --test=3Dyield --process 0 0

1. https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-October/135700.html

Signed-off-by: Michael Neuling <redacted>
--
v3:
  Fix line wrapping (WTF sorry!?!)
v2:
  Added missing include which broke allmodconfig (noticed by anton)

diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/pac=

a.h
index 1cc6e08..06cdaee 100644

--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h

@@ -16,6 +16,7 @@

=20
 #ifdef CONFIG_PPC64
=20
+#include <linux/string.h>
 #include <asm/types.h>
 #include <asm/lppaca.h>
 #include <asm/mmu.h>

@@ -132,7 +133,13 @@ struct paca_struct {
 #endif /* CONFIG_PPC_BOOK3E */

=20
 #ifdef CONFIG_PPC_BOOK3S
-	mm_context_t context;
+	mm_context_id_t context_id;
+#ifdef CONFIG_PPC_MM_SLICES
+	u64 context_low_slices_psize;
+	unsigned char context_high_slices_psize[SLICE_ARRAY_SIZE];
+#else
+	u16 context_sllp;
+#endif
 #endif
=20
 	/*

@@ -199,7 +206,14 @@ struct paca_struct {
 #ifdef CONFIG_PPC_BOOK3S
 static inline void copy_mm_to_paca(mm_context_t *context)
 {
-	get_paca()->context =3D *context;
+	get_paca()->context_id =3D context->id;
+#ifdef CONFIG_PPC_MM_SLICES
+	get_paca()->context_low_slices_psize =3D context->low_slices_psize;
+	memcpy(&get_paca()->context_high_slices_psize,
+	       &context->high_slices_psize, SLICE_ARRAY_SIZE);
+#else
+	get_paca()->context_sllp =3D context->sllp;
+#endif
 }
 #else
 static inline void copy_mm_to_paca(mm_context_t *context){}

diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-of=

fsets.c
index 9db7be2..d5903a9 100644

--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c

@@ -186,12 +186,12 @@ int main(void)
 	DEFINE(PACASOFTIRQEN, offsetof(struct paca_struct, soft_enabled));
 	DEFINE(PACAIRQHAPPENED, offsetof(struct paca_struct, irq_happened));
 #ifdef CONFIG_PPC_BOOK3S
-	DEFINE(PACACONTEXTID, offsetof(struct paca_struct, context.id));
+	DEFINE(PACACONTEXTID, offsetof(struct paca_struct, context_id));
 #ifdef CONFIG_PPC_MM_SLICES
 	DEFINE(PACALOWSLICESPSIZE, offsetof(struct paca_struct,
-					    context.low_slices_psize));
+					    context_low_slices_psize));
 	DEFINE(PACAHIGHSLICEPSIZE, offsetof(struct paca_struct,
-					    context.high_slices_psize));
+					    context_high_slices_psize));
 	DEFINE(MMUPSIZEDEFSIZE, sizeof(struct mmu_psize_def));
 #endif /* CONFIG_PPC_MM_SLICES */
 #endif

@@ -224,7 +224,7 @@ int main(void)
 #ifdef CONFIG_PPC_MM_SLICES
 	DEFINE(MMUPSIZESLLP, offsetof(struct mmu_psize_def, sllp));
 #else
-	DEFINE(PACACONTEXTSLLP, offsetof(struct paca_struct, context.sllp));
+	DEFINE(PACACONTEXTSLLP, offsetof(struct paca_struct, context_sllp));
 #endif /* CONFIG_PPC_MM_SLICES */
 	DEFINE(PACA_EXGEN, offsetof(struct paca_struct, exgen));
 	DEFINE(PACA_EXMC, offsetof(struct paca_struct, exmc));

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_6=

4.c
index 0aa526e..ae98d58 100644

--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c

@@ -877,11 +877,11 @@ static unsigned int get_paca_psize(unsigned long addr=

)
 	unsigned long index, mask_index;
=20
 	if (addr < SLICE_LOW_TOP) {
-		lpsizes =3D get_paca()->context.low_slices_psize;
+		lpsizes =3D get_paca()->context_low_slices_psize;
 		index =3D GET_LOW_SLICE_INDEX(addr);
 		return (lpsizes >> (index * 4)) & 0xF;
 	}
-	hpsizes =3D get_paca()->context.high_slices_psize;
+	hpsizes =3D get_paca()->context_high_slices_psize;
 	index =3D GET_HIGH_SLICE_INDEX(addr);
 	mask_index =3D index & 0x1;
 	return (hpsizes[index >> 1] >> (mask_index * 4)) & 0xF;

Re: [1/2] powerpc: Add function to copy mm_context_t to the paca

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2016-01-11 09:14:01

On Wed, 2015-28-10 at 04:54:06 UTC, Michael Neuling wrote:

This adds a function to copy the mm->context to the paca.  This is
only a basic conversion for now but will be used more extensively in
the next patch.

This also adds #ifdef CONFIG_PPC_BOOK3S around this code since it's
not used elsewhere.

Signed-off-by: Michael Neuling <redacted>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/c395465da68bfc3a238d5bc15f

cheers

Re: [v3, 2/2] powerpc: Copy only required pieces of the mm_context_t to the paca

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2016-01-11 09:14:02

On Thu, 2015-10-12 at 22:34:42 UTC, Michael Neuling wrote:

Currently we copy the whole mm_context_t to the paca but only access a
few bits of it.  This is wasteful of space paca and also takes quite
some time in the hot path of context switching.

This patch pulls in only the required bits from the mm_context_t to
the paca and on context switch, copies only those.

Benchmarking this (On top of Anton's recent MSR context switching
changes [1]) using processes and yield shows an improvement of almost
3% on POWER8:

  http://ozlabs.org/~anton/junkcode/context_switch2.c
  ./context_switch2 --test=yield --process 0 0

1. https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-October/135700.html

Signed-off-by: Michael Neuling <redacted>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/2fc251a8dda56b71ec491bee4c

cheers

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