[PATCH] i386/x86-64/ia64: Move polling flag into thread_info_status

During some profiling I noticed that default_idle causes a lot of
memory traffic. I think that is caused by the atomic operations
to clear/set the polling flag in thread_info. There is actually
no reason to make this atomic - only the idle thread does it
to itself, other CPUs only read it. So I moved it into ti->status.

Converted i386/x86-64/ia64 for now because that was the easiest
way to fix ACPI which also manipulates these flags in its idle
function.

Cc: Nick Piggin <npiggin@novell.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/asm-ia64/thread_info.h b/include/asm-ia64/thread_info.h
index e5392c4d30c6..8bc9869e5765 100644
--- a/include/asm-ia64/thread_info.h
+++ b/include/asm-ia64/thread_info.h
@@ -27,6 +27,7 @@ struct thread_info {
         __u32 flags;                    /* thread_info flags (see TIF_*) */
         __u32 cpu;                      /* current CPU */
         __u32 last_cpu;                 /* Last CPU thread ran on */
+        __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 */
         struct restart_block restart_block;
@@ -103,4 +104,8 @@ struct thread_info {
 /* like TIF_ALLWORK_BITS but sans TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT */
 #define TIF_WORK_MASK           (TIF_ALLWORK_MASK&~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT))
 
+#define TS_POLLING              1       /* true if in idle loop and not sleeping */
+
+#define tsk_is_polling(t) ((t)->thread_info->status & TS_POLLING)
+
 #endif /* _ASM_IA64_THREAD_INFO_H */