s390/vtime: steal time exponential moving average

To be able to judge the current overcommitment ratio for a CPU add
a lowcore field with the exponential moving average of the steal time.
The average is updated every tick.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h
index cc0947e08b6ffef09419a52eb04f817535016127..5b9f10b1e55dec03c2878a6ab510cb0d128002e5 100644 (file)
--- a/arch/s390/include/asm/lowcore.h
+++ b/arch/s390/include/asm/lowcore.h
@@ -91,52 +91,53 @@ struct lowcore {
        __u64   hardirq_timer;                  /* 0x02e8 */
        __u64   softirq_timer;                  /* 0x02f0 */
        __u64   steal_timer;                    /* 0x02f8 */
-       __u64   last_update_timer;              /* 0x0300 */
-       __u64   last_update_clock;              /* 0x0308 */
-       __u64   int_clock;                      /* 0x0310 */
-       __u64   mcck_clock;                     /* 0x0318 */
-       __u64   clock_comparator;               /* 0x0320 */
-       __u64   boot_clock[2];                  /* 0x0328 */
+       __u64   avg_steal_timer;                /* 0x0300 */
+       __u64   last_update_timer;              /* 0x0308 */
+       __u64   last_update_clock;              /* 0x0310 */
+       __u64   int_clock;                      /* 0x0318*/
+       __u64   mcck_clock;                     /* 0x0320 */
+       __u64   clock_comparator;               /* 0x0328 */
+       __u64   boot_clock[2];                  /* 0x0330 */
 
        /* Current process. */
-       __u64   current_task;                   /* 0x0338 */
-       __u64   kernel_stack;                   /* 0x0340 */
+       __u64   current_task;                   /* 0x0340 */
+       __u64   kernel_stack;                   /* 0x0348 */
 
        /* Interrupt, DAT-off and restartstack. */
-       __u64   async_stack;                    /* 0x0348 */
-       __u64   nodat_stack;                    /* 0x0350 */
-       __u64   restart_stack;                  /* 0x0358 */
+       __u64   async_stack;                    /* 0x0350 */
+       __u64   nodat_stack;                    /* 0x0358 */
+       __u64   restart_stack;                  /* 0x0360 */
 
        /* Restart function and parameter. */
-       __u64   restart_fn;                     /* 0x0360 */
-       __u64   restart_data;                   /* 0x0368 */
-       __u64   restart_source;                 /* 0x0370 */
+       __u64   restart_fn;                     /* 0x0368 */
+       __u64   restart_data;                   /* 0x0370 */
+       __u64   restart_source;                 /* 0x0378 */
 
        /* Address space pointer. */
-       __u64   kernel_asce;                    /* 0x0378 */
-       __u64   user_asce;                      /* 0x0380 */
-       __u64   vdso_asce;                      /* 0x0388 */
+       __u64   kernel_asce;                    /* 0x0380 */
+       __u64   user_asce;                      /* 0x0388 */
+       __u64   vdso_asce;                      /* 0x0390 */
 
        /*
         * The lpp and current_pid fields form a
         * 64-bit value that is set as program
         * parameter with the LPP instruction.
         */
-       __u32   lpp;                            /* 0x0390 */
-       __u32   current_pid;                    /* 0x0394 */
+       __u32   lpp;                            /* 0x0398 */
+       __u32   current_pid;                    /* 0x039c */
 
        /* SMP info area */
-       __u32   cpu_nr;                         /* 0x0398 */
-       __u32   softirq_pending;                /* 0x039c */
-       __u32   preempt_count;                  /* 0x03a0 */
-       __u32   spinlock_lockval;               /* 0x03a4 */
-       __u32   spinlock_index;                 /* 0x03a8 */
-       __u32   fpu_flags;                      /* 0x03ac */
-       __u64   percpu_offset;                  /* 0x03b0 */
-       __u64   vdso_per_cpu_data;              /* 0x03b8 */
-       __u64   machine_flags;                  /* 0x03c0 */
-       __u64   gmap;                           /* 0x03c8 */
-       __u8    pad_0x03d0[0x0400-0x03d0];      /* 0x03d0 */
+       __u32   cpu_nr;                         /* 0x03a0 */
+       __u32   softirq_pending;                /* 0x03a4 */
+       __u32   preempt_count;                  /* 0x03a8 */
+       __u32   spinlock_lockval;               /* 0x03ac */
+       __u32   spinlock_index;                 /* 0x03b0 */
+       __u32   fpu_flags;                      /* 0x03b4 */
+       __u64   percpu_offset;                  /* 0x03b8 */
+       __u64   vdso_per_cpu_data;              /* 0x03c0 */
+       __u64   machine_flags;                  /* 0x03c8 */
+       __u64   gmap;                           /* 0x03d0 */
+       __u8    pad_0x03d8[0x0400-0x03d8];      /* 0x03d8 */
 
        /* br %r1 trampoline */
        __u16   br_r1_trampoline;               /* 0x0400 */

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index b198ece2aad63d70f58b2acde1c280ce5534cf7a..b8eb99685546df9919883656c8a71930737f6ee1 100644 (file)
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -266,7 +266,8 @@ static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
        lc->percpu_offset = __per_cpu_offset[cpu];
        lc->kernel_asce = S390_lowcore.kernel_asce;
        lc->machine_flags = S390_lowcore.machine_flags;
-       lc->user_timer = lc->system_timer = lc->steal_timer = 0;
+       lc->user_timer = lc->system_timer =
+               lc->steal_timer = lc->avg_steal_timer = 0;
        __ctl_store(lc->cregs_save_area, 0, 15);
        save_access_regs((unsigned int *) lc->access_regs_save_area);
        memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,

diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 98f850e00008e99a1e64e8f20a74bbaaf4910636..a69a0911ed0e82720b10b124d0153681f2c821ea 100644 (file)
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -124,7 +124,7 @@ static void account_system_index_scaled(struct task_struct *p, u64 cputime,
  */
 static int do_account_vtime(struct task_struct *tsk)
 {
-       u64 timer, clock, user, guest, system, hardirq, softirq, steal;
+       u64 timer, clock, user, guest, system, hardirq, softirq;
 
        timer = S390_lowcore.last_update_timer;
        clock = S390_lowcore.last_update_clock;
@@ -182,12 +182,6 @@ static int do_account_vtime(struct task_struct *tsk)
        if (softirq)
                account_system_index_scaled(tsk, softirq, CPUTIME_SOFTIRQ);
 
-       steal = S390_lowcore.steal_timer;
-       if ((s64) steal > 0) {
-               S390_lowcore.steal_timer = 0;
-               account_steal_time(cputime_to_nsecs(steal));
-       }
-
        return virt_timer_forward(user + guest + system + hardirq + softirq);
 }
 
@@ -213,8 +207,19 @@ void vtime_task_switch(struct task_struct *prev)
  */
 void vtime_flush(struct task_struct *tsk)
 {
+       u64 steal, avg_steal;
+
        if (do_account_vtime(tsk))
                virt_timer_expire();
+
+       steal = S390_lowcore.steal_timer;
+       avg_steal = S390_lowcore.avg_steal_timer / 2;
+       if ((s64) steal > 0) {
+               S390_lowcore.steal_timer = 0;
+               account_steal_time(steal);
+               avg_steal += steal;
+       }
+       S390_lowcore.avg_steal_timer = avg_steal;
 }
 
 /*