src/patches/suse-2.6.27.25/patches.xen/xen-netback-nr-irqs

   1 From: jbeulich@novell.com
   2 Subject: netback: reduce overhead of IRQ recording
   3 Patch-mainline: obsolete
   4
   5 Since both NR_PIRQS and NR_DYNIRQS are no longer hardcoded, the
   6 (memory) overhead of tracking which ones to send notifications to can
   7 be pretty unbounded. Also, store the dynirq rather than the raw irq
   8 to push up the limit where the type of notify_list needs to become
   9 'int' rather than 'u16'.
  10
  11 --- head-2009-02-02.orig/drivers/xen/netback/interface.c        2009-02-02 09:40:43.000000000 +0100
  12 +++ head-2009-02-02/drivers/xen/netback/interface.c     2009-02-02 10:20:51.000000000 +0100
  13 @@ -280,6 +280,7 @@ int netif_map(netif_t *netif, unsigned l
  14                 netif->dev->name, netif);
  15         if (err < 0)
  16                 goto err_hypervisor;
  17 +       BUG_ON(err < DYNIRQ_BASE || err >= DYNIRQ_BASE + NR_DYNIRQS);
  18         netif->irq = err;
  19         disable_irq(netif->irq);
  20
  21 --- head-2009-02-02.orig/drivers/xen/netback/netback.c  2008-12-23 09:35:35.000000000 +0100
  22 +++ head-2009-02-02/drivers/xen/netback/netback.c       2008-12-23 09:35:42.000000000 +0100
  23 @@ -580,8 +580,12 @@ static void net_rx_action(unsigned long
  24         static mmu_update_t rx_mmu[NET_RX_RING_SIZE];
  25         static gnttab_transfer_t grant_trans_op[NET_RX_RING_SIZE];
  26         static gnttab_copy_t grant_copy_op[NET_RX_RING_SIZE];
  27 -       static unsigned char rx_notify[NR_IRQS];
  28 +       static DECLARE_BITMAP(rx_notify, NR_DYNIRQS);
  29 +#if NR_DYNIRQS <= 0x10000
  30         static u16 notify_list[NET_RX_RING_SIZE];
  31 +#else
  32 +       static int notify_list[NET_RX_RING_SIZE];
  33 +#endif
  34         static struct netbk_rx_meta meta[NET_RX_RING_SIZE];
  35
  36         struct netrx_pending_operations npo = {
  37 @@ -730,11 +734,9 @@ static void net_rx_action(unsigned long
  38                                          nr_frags);
  39
  40                 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&netif->rx, ret);
  41 -               irq = netif->irq;
  42 -               if (ret && !rx_notify[irq]) {
  43 -                       rx_notify[irq] = 1;
  44 +               irq = netif->irq - DYNIRQ_BASE;
  45 +               if (ret && !__test_and_set_bit(irq, rx_notify))
  46                         notify_list[notify_nr++] = irq;
  47 -               }
  48
  49                 if (netif_queue_stopped(netif->dev) &&
  50                     netif_schedulable(netif) &&
  51 @@ -748,8 +750,8 @@ static void net_rx_action(unsigned long
  52
  53         while (notify_nr != 0) {
  54                 irq = notify_list[--notify_nr];
  55 -               rx_notify[irq] = 0;
  56 -               notify_remote_via_irq(irq);
  57 +               __clear_bit(irq, rx_notify);
  58 +               notify_remote_via_irq(irq + DYNIRQ_BASE);
  59         }
  60
  61         /* More work to do? */