[PATCH] s390: external call performance

The kernel uses the SIGP external call order code to signal other CPUs.  When
running with dedicated CPUs external calls don't get delivered immediately but
within a fixed polling invervall.  This can lead to delays where the system
appears to do nothing.  Replace the SIGP external call order with the SIGP
emergency call order since this one gets delivered immediately.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/s390/kernel/head.S b/arch/s390/kernel/head.S
index fc8bf5e285f6ccb187fcd81d6a810e4ffe713543..928ca65e8bb2380456a45a431d1caf64209b3fad 100644 (file)
--- a/arch/s390/kernel/head.S
+++ b/arch/s390/kernel/head.S
@@ -765,7 +765,7 @@ _stext:     basr  %r13,0                    # get base
 
 # check control registers
         stctl  %c0,%c15,0(%r15)
-       oi     2(%r15),0x20             # enable sigp external interrupts
+       oi     2(%r15),0x40             # enable sigp emergency signal
        oi     0(%r15),0x10             # switch on low address protection
         lctl   %c0,%c15,0(%r15)
 

diff --git a/arch/s390/kernel/head64.S b/arch/s390/kernel/head64.S
index 28c50bdf7d404b5a6fe66bb4c62bef9765fbea43..10bc592c36377301f0f7781ac91b9845f9fc8828 100644 (file)
--- a/arch/s390/kernel/head64.S
+++ b/arch/s390/kernel/head64.S
@@ -762,7 +762,7 @@ _stext:     basr  %r13,0                    # get base
 
 # check control registers
         stctg  %c0,%c15,0(%r15)
-       oi     6(%r15),0x20             # enable sigp external interrupts
+       oi     6(%r15),0x40             # enable sigp emergency signal
        oi     4(%r15),0x10             # switch on low address proctection
         lctlg  %c0,%c15,0(%r15)
 

diff --git a/arch/s390/kernel/s390_ext.c b/arch/s390/kernel/s390_ext.c
index 3bdd38ec71da4fadf7009049cfc6e7bf53a3f4ce..207bc511a6e31949e9394e8d7ecf4335d15eb4cb 100644 (file)
--- a/arch/s390/kernel/s390_ext.c
+++ b/arch/s390/kernel/s390_ext.c
@@ -19,7 +19,6 @@
 #include <asm/irq.h>
 
 /*
- * Simple hash strategy: index = code & 0xff;
  * ext_int_hash[index] is the start of the list for all external interrupts
  * that hash to this index. With the current set of external interrupts 
  * (0x1202 external call, 0x1004 cpu timer, 0x2401 hwc console, 0x4000
@@ -27,6 +26,11 @@
  */
 ext_int_info_t *ext_int_hash[256] = { 0, };
 
+static inline int ext_hash(__u16 code)
+{
+       return (code + (code >> 9)) & 0xff;
+}
+
 int register_external_interrupt(__u16 code, ext_int_handler_t handler)
 {
         ext_int_info_t *p;
@@ -37,7 +41,7 @@ int register_external_interrupt(__u16 code, ext_int_handler_t handler)
                 return -ENOMEM;
         p->code = code;
         p->handler = handler;
-        index = code & 0xff;
+       index = ext_hash(code);
         p->next = ext_int_hash[index];
         ext_int_hash[index] = p;
         return 0;
@@ -52,7 +56,7 @@ int register_early_external_interrupt(__u16 code, ext_int_handler_t handler,
                 return -EINVAL;
         p->code = code;
         p->handler = handler;
-        index = code & 0xff;
+       index = ext_hash(code);
         p->next = ext_int_hash[index];
         ext_int_hash[index] = p;
         return 0;
@@ -63,7 +67,7 @@ int unregister_external_interrupt(__u16 code, ext_int_handler_t handler)
         ext_int_info_t *p, *q;
         int index;
 
-        index = code & 0xff;
+       index = ext_hash(code);
         q = NULL;
         p = ext_int_hash[index];
         while (p != NULL) {
@@ -90,7 +94,7 @@ int unregister_early_external_interrupt(__u16 code, ext_int_handler_t handler,
 
        if (p == NULL || p->code != code || p->handler != handler)
                return -EINVAL;
-       index = code & 0xff;
+       index = ext_hash(code);
        q = ext_int_hash[index];
        if (p != q) {
                while (q != NULL) {
@@ -120,7 +124,7 @@ void do_extint(struct pt_regs *regs, unsigned short code)
                 */
                account_ticks(regs);
        kstat_cpu(smp_processor_id()).irqs[EXTERNAL_INTERRUPT]++;
-        index = code & 0xff;
+        index = ext_hash(code);
        for (p = ext_int_hash[index]; p; p = p->next) {
                if (likely(p->code == code)) {
                        if (likely(p->handler))

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 642572a8e334d435e988c935673437b666ceda95..da77f001af8ddbf5687ded085fbffb4c3baadb5d 100644 (file)
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -375,7 +375,7 @@ static void smp_ext_bitcall(int cpu, ec_bit_sig sig)
          * Set signaling bit in lowcore of target cpu and kick it
          */
        set_bit(sig, (unsigned long *) &lowcore_ptr[cpu]->ext_call_fast);
-       while(signal_processor(cpu, sigp_external_call) == sigp_busy)
+       while(signal_processor(cpu, sigp_emergency_signal) == sigp_busy)
                udelay(10);
 }
 
@@ -394,7 +394,7 @@ static void smp_ext_bitcall_others(ec_bit_sig sig)
                  * Set signaling bit in lowcore of target cpu and kick it
                  */
                set_bit(sig, (unsigned long *) &lowcore_ptr[cpu]->ext_call_fast);
-               while (signal_processor(cpu, sigp_external_call) == sigp_busy)
+               while (signal_processor(cpu, sigp_emergency_signal) == sigp_busy)
                        udelay(10);
         }
 }
@@ -751,9 +751,9 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
        unsigned int cpu;
         int i;
 
-        /* request the 0x1202 external interrupt */
-        if (register_external_interrupt(0x1202, do_ext_call_interrupt) != 0)
-                panic("Couldn't request external interrupt 0x1202");
+        /* request the 0x1201 emergency signal external interrupt */
+        if (register_external_interrupt(0x1201, do_ext_call_interrupt) != 0)
+                panic("Couldn't request external interrupt 0x1201");
         smp_check_cpus(max_cpus);
         memset(lowcore_ptr,0,sizeof(lowcore_ptr));  
         /*