src/patches/suse-2.6.27.39/patches.arch/s390-17-perf-08-qdio_merge_AI_tasklet_into_interrupt_handler.patch

   1 From: Gerald Schaefer <geraldsc@de.ibm.com>
   2 Subject: [PATCH] qdio: merge AI tasklet into interrupt handler
   3 References: bnc#532063,LTC#55526
   4
   5 From: Jan Glauber <jang@linux.vnet.ibm.com>
   6
   7 Since the adapter interrupt tasklet only schedules the queue tasklets
   8 and contains no code that requires serialization in can be merged
   9 with the adapter interrupt handler. That possibly safes some CPU
  10 cycles.
  11
  12 Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
  13
  14 Acked-by: John Jolly <jjolly@suse.de>
  15
  16 ---
  17  drivers/s390/cio/qdio_thinint.c |   66 ++++++++++++----------------------------
  18  1 file changed, 21 insertions(+), 45 deletions(-)
  19
  20 Index: linux-sles11/drivers/s390/cio/qdio_thinint.c
  21 ===================================================================
  22 --- linux-sles11.orig/drivers/s390/cio/qdio_thinint.c
  23 +++ linux-sles11/drivers/s390/cio/qdio_thinint.c
  24 @@ -43,9 +43,6 @@ struct indicator_t {
  25  };
  26  static struct indicator_t *q_indicators;
  27
  28 -static void tiqdio_tasklet_fn(unsigned long data);
  29 -static DECLARE_TASKLET(tiqdio_tasklet, tiqdio_tasklet_fn, 0);
  30 -
  31  static int css_qdio_omit_svs;
  32
  33  static inline unsigned long do_clear_global_summary(void)
  34 @@ -103,11 +100,6 @@ void tiqdio_add_input_queues(struct qdio
  35         xchg(irq_ptr->dsci, 1);
  36  }
  37
  38 -/*
  39 - * we cannot stop the tiqdio tasklet here since it is for all
  40 - * thinint qdio devices and it must run as long as there is a
  41 - * thinint device left
  42 - */
  43  void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)
  44  {
  45         struct qdio_q *q;
  46 @@ -131,17 +123,34 @@ static inline int shared_ind(struct qdio
  47         return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
  48  }
  49
  50 -/* check for work on all inbound thinint queues */
  51 -static void tiqdio_tasklet_fn(unsigned long data)
  52 +/**
  53 + * tiqdio_thinint_handler - thin interrupt handler for qdio
  54 + * @ind: pointer to adapter local summary indicator
  55 + * @drv_data: NULL
  56 + */
  57 +static void tiqdio_thinint_handler(void *ind, void *drv_data)
  58  {
  59         struct qdio_q *q;
  60
  61 -       qdio_perf_stat_inc(&perf_stats.tasklet_thinint);
  62 -again:
  63 +       qdio_perf_stat_inc(&perf_stats.thin_int);
  64 +
  65 +       /*
  66 +        * SVS only when needed: issue SVS to benefit from iqdio interrupt
  67 +        * avoidance (SVS clears adapter interrupt suppression overwrite)
  68 +        */
  69 +       if (!css_qdio_omit_svs)
  70 +               do_clear_global_summary();
  71 +
  72 +       /*
  73 +        * reset local summary indicator (tiqdio_alsi) to stop adapter
  74 +        * interrupts for now
  75 +        */
  76 +       xchg((u8 *)ind, 0);
  77
  78         /* protect tiq_list entries, only changed in activate or shutdown */
  79         rcu_read_lock();
  80
  81 +       /* check for work on all inbound thinint queues */
  82         list_for_each_entry_rcu(q, &tiq_list, entry)
  83                 /* only process queues from changed sets */
  84                 if (*q->irq_ptr->dsci) {
  85 @@ -169,37 +178,6 @@ again:
  86                 if (*tiqdio_alsi)
  87                         xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 1);
  88         }
  89 -
  90 -       /* check for more work */
  91 -       if (*tiqdio_alsi) {
  92 -               xchg(tiqdio_alsi, 0);
  93 -               qdio_perf_stat_inc(&perf_stats.tasklet_thinint_loop);
  94 -               goto again;
  95 -       }
  96 -}
  97 -
  98 -/**
  99 - * tiqdio_thinint_handler - thin interrupt handler for qdio
 100 - * @ind: pointer to adapter local summary indicator
 101 - * @drv_data: NULL
 102 - */
 103 -static void tiqdio_thinint_handler(void *ind, void *drv_data)
 104 -{
 105 -       qdio_perf_stat_inc(&perf_stats.thin_int);
 106 -
 107 -       /*
 108 -        * SVS only when needed: issue SVS to benefit from iqdio interrupt
 109 -        * avoidance (SVS clears adapter interrupt suppression overwrite)
 110 -        */
 111 -       if (!css_qdio_omit_svs)
 112 -               do_clear_global_summary();
 113 -
 114 -       /*
 115 -        * reset local summary indicator (tiqdio_alsi) to stop adapter
 116 -        * interrupts for now, the tasklet will clean all dsci's
 117 -        */
 118 -       xchg((u8 *)ind, 0);
 119 -       tasklet_hi_schedule(&tiqdio_tasklet);
 120  }
 121
 122  static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
 123 @@ -313,8 +291,6 @@ void qdio_shutdown_thinint(struct qdio_i
 124
 125  void __exit tiqdio_unregister_thinints(void)
 126  {
 127 -       tasklet_disable(&tiqdio_tasklet);
 128 -
 129         if (tiqdio_alsi) {
 130                 s390_unregister_adapter_interrupt(tiqdio_alsi, QDIO_AIRQ_ISC);
 131                 isc_unregister(QDIO_AIRQ_ISC);