[RFC] Thread Migration Preemption

From: Mathieu Desnoyers
Date: Thu Jul 05 2007 - 17:52:09 EST

Thread Migration Preemption

This patch adds the ability to protect critical sections from migration to
another CPU without disabling preemption.

This will be useful to minimize the amount of preemption disabling for the -rt
patch. It will help leveraging improvements brought by the local_t types in
asm/local.h (see Documentation/local_ops.txt). Note that the updates done to
variables protected by migration_disable must be either atomic or protected from
concurrent updates done by other threads.

Typical use:

migration_disable();
local_inc(&__get_cpu_var(&my_local_t_var));
migration_enable();

Which will increment the variable atomically wrt the local CPU.

Comments (such as how to integrate this in the already almost full
preempt_count) are welcome.

It applies on 2.6.22-rc6-mm1.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>
---
include/asm-alpha/thread_info.h | 1 +
include/asm-arm/thread_info.h | 2 ++
include/asm-arm26/thread_info.h | 2 ++
include/asm-avr32/thread_info.h | 2 ++
include/asm-blackfin/thread_info.h | 2 ++
include/asm-cris/thread_info.h | 2 ++
include/asm-frv/thread_info.h | 2 ++
include/asm-h8300/thread_info.h | 2 ++
include/asm-i386/thread_info.h | 4 ++--
include/asm-ia64/thread_info.h | 2 ++
include/asm-m32r/thread_info.h | 2 ++
include/asm-m68k/thread_info.h | 1 +
include/asm-m68knommu/thread_info.h | 1 +
include/asm-mips/thread_info.h | 2 ++
include/asm-parisc/thread_info.h | 2 ++
include/asm-powerpc/thread_info.h | 2 ++
include/asm-s390/thread_info.h | 2 ++
include/asm-sh/thread_info.h | 2 ++
include/asm-sh64/thread_info.h | 2 ++
include/asm-sparc/thread_info.h | 2 ++
include/asm-sparc64/thread_info.h | 2 ++
include/asm-um/thread_info.h | 2 ++
include/asm-v850/thread_info.h | 2 ++
include/asm-x86_64/thread_info.h | 2 ++
include/asm-xtensa/thread_info.h | 2 ++
include/linux/preempt.h | 26 +++++++++++++++++++++++++-
kernel/sched.c | 26 ++++++++++++++++++++++++++
27 files changed, 98 insertions(+), 3 deletions(-)

Index: linux-2.6-lttng/include/asm-i386/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-i386/thread_info.h 2007-07-05 16:23:14.000000000 -0400
+++ linux-2.6-lttng/include/asm-i386/thread_info.h 2007-07-05 17:50:51.000000000 -0400
@@ -31,8 +31,7 @@
unsigned long status; /* thread-synchronous flags */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
-
-
+ int migration_count;/* 0: can migrate, <0: BUG */
mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
0-0xFFFFFFFF for kernel-thread
@@ -74,6 +73,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
Index: linux-2.6-lttng/include/linux/preempt.h
===================================================================
--- linux-2.6-lttng.orig/include/linux/preempt.h 2007-07-05 16:19:00.000000000 -0400
+++ linux-2.6-lttng/include/linux/preempt.h 2007-07-05 16:33:29.000000000 -0400
@@ -12,15 +12,24 @@
#ifdef CONFIG_DEBUG_PREEMPT
extern void fastcall add_preempt_count(int val);
extern void fastcall sub_preempt_count(int val);
+ extern void fastcall add_migration_count(int val);
+ extern void fastcall sub_migration_count(int val);
#else
# define add_preempt_count(val) do { preempt_count() += (val); } while (0)
# define sub_preempt_count(val) do { preempt_count() -= (val); } while (0)
+# define add_migration_count(val) do { migration_count() += (val); } while (0)
+# define sub_migration_count(val) do { migration_count() -= (val); } while (0)
#endif

#define inc_preempt_count() add_preempt_count(1)
#define dec_preempt_count() sub_preempt_count(1)

-#define preempt_count() (current_thread_info()->preempt_count)
+#define preempt_count() (current_thread_info()->preempt_count)
+
+#define inc_migration_count() add_migration_count(1)
+#define dec_migration_count() sub_migration_count(1)
+
+#define migration_count() (current_thread_info()->migration_count)

#ifdef CONFIG_PREEMPT

@@ -51,6 +60,18 @@
preempt_check_resched(); \
} while (0)

+#define migration_disable() \
+do { \
+ inc_migration_count(); \
+ barrier(); \
+} while (0)
+
+#define migration_enable() \
+do { \
+ barrier(); \
+ dec_migration_count(); \
+} while (0)
+
#else

#define preempt_disable() do { } while (0)
@@ -58,6 +79,9 @@
#define preempt_enable() do { } while (0)
#define preempt_check_resched() do { } while (0)

+#define migration_disable() do { } while (0)
+#define migration_enable() do { } while (0)
+
#endif

#endif /* __LINUX_PREEMPT_H */
Index: linux-2.6-lttng/kernel/sched.c
===================================================================
--- linux-2.6-lttng.orig/kernel/sched.c 2007-07-05 16:28:15.000000000 -0400
+++ linux-2.6-lttng/kernel/sched.c 2007-07-05 16:53:24.000000000 -0400
@@ -1996,6 +1996,7 @@
* 1) running (obviously), or
* 2) cannot be migrated to this CPU due to cpus_allowed, or
* 3) are cache-hot on their current CPU.
+ * 4) migration preemption is non 0 for this non running task.
*/
if (!cpu_isset(this_cpu, p->cpus_allowed))
return 0;
@@ -2003,6 +2004,8 @@

if (task_running(rq, p))
return 0;
+ if (task_thread_info(p)->migration_count)
+ return 0;

/*
* Aggressive migration if too many balance attempts have failed:
@@ -3220,6 +3223,29 @@
}
EXPORT_SYMBOL(sub_preempt_count);

+void fastcall add_migration_count(int val)
+{
+ /*
+ * Underflow?
+ */
+ if (DEBUG_LOCKS_WARN_ON((migration_count() < 0)))
+ return;
+ migration_count() += val;
+}
+EXPORT_SYMBOL(add_migration_count);
+
+void fastcall sub_migration_count(int val)
+{
+ /*
+ * Underflow?
+ */
+ if (DEBUG_LOCKS_WARN_ON(val > migration_count()))
+ return;
+
+ migration_count() -= val;
+}
+EXPORT_SYMBOL(sub_migration_count);
+
#endif

/*
Index: linux-2.6-lttng/include/asm-alpha/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-alpha/thread_info.h 2007-07-05 16:54:49.000000000 -0400
+++ linux-2.6-lttng/include/asm-alpha/thread_info.h 2007-07-05 16:55:39.000000000 -0400
@@ -21,6 +21,7 @@
mm_segment_t addr_limit; /* thread address space */
unsigned cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */

int bpt_nsaved;
unsigned long bpt_addr[2]; /* breakpoint handling */
Index: linux-2.6-lttng/include/asm-arm/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-arm/thread_info.h 2007-07-05 16:54:49.000000000 -0400
+++ linux-2.6-lttng/include/asm-arm/thread_info.h 2007-07-05 17:00:39.000000000 -0400
@@ -51,6 +51,7 @@
struct thread_info {
unsigned long flags; /* low level flags */
int preempt_count; /* 0 => preemptable, <0 => bug */
+ int migration_count;/* 0: can migrate, <0 => BUG */
mm_segment_t addr_limit; /* address limit */
struct task_struct *task; /* main task structure */
struct exec_domain *exec_domain; /* execution domain */
@@ -72,6 +73,7 @@
.exec_domain = &default_exec_domain, \
.flags = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.addr_limit = KERNEL_DS, \
.cpu_domain = domain_val(DOMAIN_USER, DOMAIN_MANAGER) | \
domain_val(DOMAIN_KERNEL, DOMAIN_MANAGER) | \
Index: linux-2.6-lttng/include/asm-arm26/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-arm26/thread_info.h 2007-07-05 16:54:49.000000000 -0400
+++ linux-2.6-lttng/include/asm-arm26/thread_info.h 2007-07-05 16:59:55.000000000 -0400
@@ -45,6 +45,7 @@
struct thread_info {
unsigned long flags; /* low level flags */
int preempt_count; /* 0 => preemptable, <0 => bug */
+ int migration_count;/* 0: can migrate, <0 => BUG */
mm_segment_t addr_limit; /* address limit */
struct task_struct *task; /* main task structure */
struct exec_domain *exec_domain; /* execution domain */
@@ -60,6 +61,7 @@
.exec_domain &default_exec_domain, \
.flags 0, \
.preempt_count 0, \
+ .migration_count 0, \
.addr_limit KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
Index: linux-2.6-lttng/include/asm-avr32/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-avr32/thread_info.h 2007-07-05 16:54:49.000000000 -0400
+++ linux-2.6-lttng/include/asm-avr32/thread_info.h 2007-07-05 17:00:52.000000000 -0400
@@ -25,6 +25,7 @@
unsigned long flags; /* low level flags */
__u32 cpu;
__s32 preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
__u8 supervisor_stack[0];
};
@@ -36,6 +37,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall \
} \
Index: linux-2.6-lttng/include/asm-blackfin/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-blackfin/thread_info.h 2007-07-05 16:54:49.000000000 -0400
+++ linux-2.6-lttng/include/asm-blackfin/thread_info.h 2007-07-05 17:00:58.000000000 -0400
@@ -54,6 +54,7 @@
unsigned long flags; /* low level flags */
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count; /* 0: can migrate, <0 => BUG */
mm_segment_t addr_limit; /* address limit */
struct restart_block restart_block;
struct l1_scratch_task_info l1_task_info;
@@ -69,6 +70,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
Index: linux-2.6-lttng/include/asm-cris/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-cris/thread_info.h 2007-07-05 16:54:49.000000000 -0400
+++ linux-2.6-lttng/include/asm-cris/thread_info.h 2007-07-05 17:01:16.000000000 -0400
@@ -32,6 +32,7 @@
unsigned long flags; /* low level flags */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */

mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
@@ -58,6 +59,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
Index: linux-2.6-lttng/include/asm-frv/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-frv/thread_info.h 2007-07-05 16:54:49.000000000 -0400
+++ linux-2.6-lttng/include/asm-frv/thread_info.h 2007-07-05 17:01:28.000000000 -0400
@@ -36,6 +36,7 @@
unsigned long status; /* thread-synchronous flags */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */

mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
@@ -68,6 +69,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
Index: linux-2.6-lttng/include/asm-h8300/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-h8300/thread_info.h 2007-07-05 16:54:49.000000000 -0400
+++ linux-2.6-lttng/include/asm-h8300/thread_info.h 2007-07-05 17:01:52.000000000 -0400
@@ -24,6 +24,7 @@
unsigned long flags; /* low level flags */
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
};

@@ -37,6 +38,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
Index: linux-2.6-lttng/include/asm-ia64/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-ia64/thread_info.h 2007-07-05 16:54:49.000000000 -0400
+++ linux-2.6-lttng/include/asm-ia64/thread_info.h 2007-07-05 17:02:31.000000000 -0400
@@ -30,6 +30,7 @@
__u32 status; /* Thread synchronous flags */
mm_segment_t addr_limit; /* user-level address space limit */
int preempt_count; /* 0=premptable, <0=BUG; will also serve as bh-counter */
+ int migration_count; /* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
};

@@ -43,6 +44,7 @@
.cpu = 0, \
.addr_limit = KERNEL_DS, \
.preempt_count = 0, \
+ .migration_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
Index: linux-2.6-lttng/include/asm-m32r/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-m32r/thread_info.h 2007-07-05 16:54:49.000000000 -0400
+++ linux-2.6-lttng/include/asm-m32r/thread_info.h 2007-07-05 17:02:44.000000000 -0400
@@ -29,6 +29,7 @@
unsigned long status; /* thread-synchronous flags */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */

mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thread
@@ -69,6 +70,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
Index: linux-2.6-lttng/include/asm-m68k/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-m68k/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-m68k/thread_info.h 2007-07-05 17:02:59.000000000 -0400
@@ -9,6 +9,7 @@
unsigned long flags;
struct exec_domain *exec_domain; /* execution domain */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */
__u32 cpu; /* should always be 0 on m68k */
struct restart_block restart_block;
};
Index: linux-2.6-lttng/include/asm-m68knommu/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-m68knommu/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-m68knommu/thread_info.h 2007-07-05 17:02:56.000000000 -0400
@@ -37,6 +37,7 @@
unsigned long flags; /* low level flags */
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count; /* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
};

Index: linux-2.6-lttng/include/asm-mips/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-mips/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-mips/thread_info.h 2007-07-05 17:03:14.000000000 -0400
@@ -28,6 +28,7 @@
unsigned long tp_value; /* thread pointer */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */

mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
@@ -49,6 +50,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
Index: linux-2.6-lttng/include/asm-parisc/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-parisc/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-parisc/thread_info.h 2007-07-05 17:03:27.000000000 -0400
@@ -13,6 +13,7 @@
mm_segment_t addr_limit; /* user-level address space limit */
__u32 cpu; /* current CPU */
int preempt_count; /* 0=premptable, <0=BUG; will also serve as bh-counter */
+ int migration_count; /* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
};

@@ -24,6 +25,7 @@
.cpu = 0, \
.addr_limit = KERNEL_DS, \
.preempt_count = 1, \
+ .migration_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall \
} \
Index: linux-2.6-lttng/include/asm-powerpc/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-powerpc/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-powerpc/thread_info.h 2007-07-05 17:03:47.000000000 -0400
@@ -35,6 +35,7 @@
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable,
<0 => BUG */
+ int migration_count; /* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
unsigned long local_flags; /* private flags for thread */

@@ -53,6 +54,7 @@
.exec_domain = &default_exec_domain, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
Index: linux-2.6-lttng/include/asm-s390/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-s390/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-s390/thread_info.h 2007-07-05 17:04:04.000000000 -0400
@@ -51,6 +51,7 @@
unsigned long flags; /* low level flags */
unsigned int cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
};

@@ -64,6 +65,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
Index: linux-2.6-lttng/include/asm-sh/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-sh/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-sh/thread_info.h 2007-07-05 17:04:32.000000000 -0400
@@ -21,6 +21,7 @@
unsigned long flags; /* low level flags */
__u32 cpu;
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */
mm_segment_t addr_limit; /* thread address space */
struct restart_block restart_block;
unsigned long previous_sp; /* sp of previous stack in case
@@ -58,6 +59,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
Index: linux-2.6-lttng/include/asm-sh64/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-sh64/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-sh64/thread_info.h 2007-07-05 17:04:18.000000000 -0400
@@ -23,6 +23,7 @@
unsigned long flags; /* low level flags */
/* Put the 4 32-bit fields together to make asm offsetting easier. */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */
__u16 cpu;

mm_segment_t addr_limit;
@@ -41,6 +42,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
Index: linux-2.6-lttng/include/asm-sparc/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-sparc/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-sparc/thread_info.h 2007-07-05 17:05:16.000000000 -0400
@@ -33,6 +33,7 @@
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable,
<0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */
int softirq_count;
int hardirq_count;

@@ -65,6 +66,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
Index: linux-2.6-lttng/include/asm-sparc64/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-sparc64/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-sparc64/thread_info.h 2007-07-05 17:05:00.000000000 -0400
@@ -47,6 +47,7 @@
struct pt_regs *kregs;
struct exec_domain *exec_domain;
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */
__u8 new_child;
__u8 syscall_noerror;
__u16 cpu;
@@ -137,6 +138,7 @@
.flags = ((unsigned long)ASI_P) << TI_FLAG_CURRENT_DS_SHIFT, \
.exec_domain = &default_exec_domain, \
.preempt_count = 1, \
+ .migration_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
Index: linux-2.6-lttng/include/asm-um/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-um/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-um/thread_info.h 2007-07-05 17:05:30.000000000 -0400
@@ -18,6 +18,7 @@
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable,
<0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */
mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user
0-0xFFFFFFFF for kernel */
@@ -32,6 +33,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
Index: linux-2.6-lttng/include/asm-v850/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-v850/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-v850/thread_info.h 2007-07-05 17:05:41.000000000 -0400
@@ -32,6 +32,7 @@
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable,
<0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
};

@@ -42,6 +43,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
Index: linux-2.6-lttng/include/asm-x86_64/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-x86_64/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-x86_64/thread_info.h 2007-07-05 17:05:49.000000000 -0400
@@ -30,6 +30,7 @@
__u32 status; /* thread synchronous flags */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migration_count;/* 0: can migrate, <0 => BUG */

mm_segment_t addr_limit;
struct restart_block restart_block;
@@ -48,6 +49,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
Index: linux-2.6-lttng/include/asm-xtensa/thread_info.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-xtensa/thread_info.h 2007-07-05 16:54:50.000000000 -0400
+++ linux-2.6-lttng/include/asm-xtensa/thread_info.h 2007-07-05 17:06:07.000000000 -0400
@@ -34,6 +34,7 @@
unsigned long status; /* thread-synchronous flags */
__u32 cpu; /* current CPU */
__s32 preempt_count; /* 0 => preemptable,< 0 => BUG*/
+ __s32 migration_count;/* 0: can migrate, <0 => BUG */

mm_segment_t addr_limit; /* thread address space */
struct restart_block restart_block;
@@ -72,6 +73,7 @@
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migration_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \

--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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