bitkeeper revision 1.1278.1.1 (4254b244uWvJejlkGeqN8mp1CLtN5w)

New Xen trace buffer implementation that avoids blocking
interrupts. Add support for trace buffer CPU mask and
event mask. Add support for trace classes. New DOM0 trace
buffer hypercall. Fix 'xentrace' signal handler bug.

Signed-off-by: bin.ren@cl.cam.ac.uk

1 files changed, 34 insertions, 27 deletions

diff --git a/xen/include/xen/trace.h b/xen/include/xen/trace.h
index 88c0b23d39..e46d916c32 100644
--- a/xen/include/xen/trace.h
+++ b/xen/include/xen/trace.h
@@ -8,6 +8,8 @@
  * Author: Mark Williamson, mark.a.williamson@intel.com
  * Date:   January 2004
  *
+ * Copyright (C) 2005 Bin Ren
+ *
  * The trace buffer code is designed to allow debugging traces of Xen to be
  * generated on UP / SMP machines.  Each trace entry is timestamped so that
  * it's possible to reconstruct a chronological record of trace events.
@@ -25,7 +27,6 @@
 
 #ifdef TRACE_BUFFER
 
-#include <xen/spinlock.h>
 #include <asm/page.h>
 #include <xen/types.h>
 #include <xen/sched.h>
@@ -34,11 +35,16 @@
 #include <asm/msr.h>
 #include <public/dom0_ops.h>
 
+extern struct t_buf *t_bufs[];
+extern int tb_init_done;
+extern unsigned long tb_cpu_mask;
+extern u32 tb_event_mask;
+
 /* Used to initialise trace buffer functionality */
 void init_trace_bufs(void);
 
 /* used to retrieve the physical address of the trace buffers */
-int get_tb_info(dom0_gettbufs_t *st);
+int tb_control(dom0_tbufcontrol_t *tbc);
 
 /**
  * trace - Enters a trace tuple into the trace buffer for the current CPU.
@@ -49,42 +55,43 @@ int get_tb_info(dom0_gettbufs_t *st);
  * failure, otherwise 0.  Failure occurs only if the trace buffers are not yet
  * initialised.
  */
-static inline int trace(u32 event, u32 d1, u32 d2, u32 d3, u32 d4, u32 d5)
+static inline int trace(u32 event, unsigned long d1, unsigned long d2,
+                        unsigned long d3, unsigned long d4, unsigned long d5)
 {
-    extern struct t_buf *t_bufs[];      /* global array of pointers to bufs */
-    extern int tb_init_done;            /* set when buffers are initialised */
-    unsigned long flags;                /* for saving interrupt flags       */
-    struct t_buf *buf;                  /* the buffer we're working on      */
-    struct t_rec *rec;                  /* next record to fill out          */
-
+    atomic_t old, new, seen;
+    struct t_buf *buf;
+    struct t_rec *rec;
 
     if ( !tb_init_done )
         return -1;
 
+    if ( (tb_event_mask & event) == 0 )
+        return 0;
+
+    if ( (tb_cpu_mask & (1UL << smp_processor_id())) == 0 )
+        return 0;
 
     buf = t_bufs[smp_processor_id()];
 
-    local_irq_save(flags);
+    do
+    {
+        old = buf->rec_idx;
+        _atomic_set(new, (_atomic_read(old) + 1) % buf->rec_num);
+        seen = atomic_compareandswap(old, new, &buf->rec_idx);
+    }
+    while ( unlikely(_atomic_read(seen) != _atomic_read(old)) );
 
-    rec = buf->head_ptr;
+    wmb();
 
+    rec = &buf->rec[_atomic_read(old)];
     rdtscll(rec->cycles);
-    rec->event = event;
-    rec->d1 = d1;
-    rec->d2 = d2;
-    rec->d3 = d3;
-    rec->d4 = d4;
-    rec->d5 = d5;
-
-    wmb(); /* above must be visible before reader sees index updated */
-
-    buf->head_ptr++;
-    buf->head++;
-    if ( buf->head_ptr == (buf->vdata + buf->size) )
-        buf->head_ptr = buf->vdata;
-
-    local_irq_restore(flags);
-    
+    rec->event   = event;
+    rec->data[0] = d1;
+    rec->data[1] = d2;
+    rec->data[2] = d3;
+    rec->data[3] = d4;
+    rec->data[4] = d5;
+
     return 0;
 }