1 files changed, 10 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
index 6fbd19564e4e..9e9a70e50c72 100644
--- a/arch/x86_64/kernel/process.c
+++ b/arch/x86_64/kernel/process.c
@@ -552,6 +552,10 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
         int cpu = smp_processor_id();  
         struct tss_struct *tss = &per_cpu(init_tss, cpu);
 
+        /* we're going to use this soon, after a few expensive things */
+        if (next_p->fpu_counter>5)
+                prefetch(&next->i387.fxsave);
+
         /*
          * Reload esp0, LDT and the page table pointer:
          */
@@ -629,6 +633,12 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
             || test_tsk_thread_flag(prev_p, TIF_IO_BITMAP))
                 __switch_to_xtra(prev_p, next_p, tss);
 
+        /* If the task has used fpu the last 5 timeslices, just do a full
+         * restore of the math state immediately to avoid the trap; the
+         * chances of needing FPU soon are obviously high now
+         */
+        if (next_p->fpu_counter>5)
+                math_state_restore();
         return prev_p;
 }