# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Node ID e05d60be5adb22afc42d18d631041cc6e2ccbe91
# Parent 3cdb93867f817243f6e770baf72c58a40d33de5c
[XENTRACE] Remember number of lost trace records when
trace buffer is full and write a 'number of lost records'
entry when space becomes available.
From: Rob Gardner <rob.gardner@xxxxxx>
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
xen/common/trace.c | 23 ++++++++++++++++++++---
xen/include/public/trace.h | 1 +
2 files changed, 21 insertions(+), 3 deletions(-)
diff -r 3cdb93867f81 -r e05d60be5adb xen/common/trace.c
--- a/xen/common/trace.c Mon Jul 10 16:09:20 2006 +0100
+++ b/xen/common/trace.c Mon Jul 10 17:05:44 2006 +0100
@@ -46,6 +46,8 @@ static int nr_recs;
/* Send virtual interrupt when buffer level reaches this point */
static int t_buf_highwater;
+/* Number of records lost due to per-CPU trace buffer being full. */
+static DEFINE_PER_CPU(unsigned long, lost_records);
/* a flag recording whether initialization has been done */
/* or more properly, if the tbuf subsystem is enabled right now */
@@ -234,7 +236,7 @@ void trace(u32 event, unsigned long d1,
struct t_buf *buf;
struct t_rec *rec;
unsigned long flags;
-
+
BUG_ON(!tb_init_done);
if ( (tb_event_mask & event) == 0 )
@@ -259,10 +261,25 @@ void trace(u32 event, unsigned long d1,
local_irq_save(flags);
- if ( (buf->prod - buf->cons) >= nr_recs )
- {
+ /* Check if space for two records (we write two if there are lost recs). */
+ if ( (buf->prod - buf->cons) >= (nr_recs - 1) )
+ {
+ this_cpu(lost_records)++;
local_irq_restore(flags);
return;
+ }
+
+ if ( unlikely(this_cpu(lost_records) != 0) )
+ {
+ rec = &t_recs[smp_processor_id()][buf->prod % nr_recs];
+ memset(rec, 0, sizeof(*rec));
+ rec->cycles = (u64)get_cycles();
+ rec->event = TRC_LOST_RECORDS;
+ rec->data[0] = this_cpu(lost_records);
+ this_cpu(lost_records) = 0;
+
+ wmb();
+ buf->prod++;
}
rec = &t_recs[smp_processor_id()][buf->prod % nr_recs];
diff -r 3cdb93867f81 -r e05d60be5adb xen/include/public/trace.h
--- a/xen/include/public/trace.h Mon Jul 10 16:09:20 2006 +0100
+++ b/xen/include/public/trace.h Mon Jul 10 17:05:44 2006 +0100
@@ -26,6 +26,7 @@
#define TRC_VMXIO 0x00088000 /* VMX io emulation trace */
/* Trace events per class */
+#define TRC_LOST_RECORDS (TRC_GEN + 1)
#define TRC_SCHED_DOM_ADD (TRC_SCHED + 1)
#define TRC_SCHED_DOM_REM (TRC_SCHED + 2)
_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog
|
Home