Demonstrate using an asynchronous probe (the os timer)

1 files changed, 138 insertions, 0 deletions

diff --git a/runtime/probes/os_timer/os_timer.c b/runtime/probes/os_timer/os_timer.c
new file mode 100644
index 00000000..f40b4168
--- /dev/null
+++ b/runtime/probes/os_timer/os_timer.c
@@ -0,0 +1,138 @@
+/* Use the os timer as a poor-man's time based profiler for a UP system */
+
+/* Demonstrates the beginnings of a generic framework for */
+/* asynchronous probes using the runtime */
+
+/* @todo NOTE: the statement: regs = task_pt_regs(current); */
+/* isn't working in the way I would expect. The timer callback */
+/* happens, but I don't get a reasonable value in regs->eip */
+/* Can this routine be called during the timer callback? */
+
+/* os includes */
+#include "linux/timer.h"
+
+/* define this if you don't want to use relayfs.  Normally */
+/* you want relayfs, unless you need a realtime stream of data */
+
+/* #define STP_NETLINK_ONLY */
+
+/* How many strings to allocate. see strings.c. Default is 0. */
+#define STP_NUM_STRINGS 1
+
+/* maximum size for a string. default is 2048 */
+#define STP_STRING_SIZE 2048
+
+/* size of strings saved in maps */
+#define MAP_STRING_LENGTH 256
+
+/* width of histograms. Default 50 */
+#define HIST_WIDTH 50
+
+/* always include this.  Put all non-map defines above it. */
+#include "runtime.h"
+
+/* since we don't have aggregation maps yet, try regular maps */
+#define NEED_INT64_VALS
+
+#define KEY1_TYPE INT64
+#include "map-keys.c"
+
+#include "map.c"
+
+#include "stat.c"
+#include "stack.c"
+
+MODULE_DESCRIPTION("SystemTap probe: os_timer");
+MODULE_AUTHOR("Charles Spirakis <charles.spirakis@intel.com>");
+
+Stat addr;
+MAP cur_addr;
+
+/* A generic asynchorous probe entry point */
+void inst_async(struct pt_regs *regs)
+{
+    unsigned long ip = regs->eip;
+
+    /* can we generate a histogram of ip addresses seen? */
+    _stp_stat_add(addr, 1);
+
+    /* Create a map of interrupted addresses seen */
+    /* really want a map of image name / address */
+    _stp_map_key_int64(cur_addr, ip);
+    _stp_map_add_int64(cur_addr, 1);
+
+    /* Need _stp_stack() and _stp_ustack()? */
+    /* _stp_image() and aggregation maps */
+}
+
+static struct timer_list timer;
+
+/* Helper function to convert from os timer callback into */
+/* generic asynchronous entry point form */
+static void os_timer_callback(unsigned long val)
+{
+    struct pt_regs *regs;
+
+    /* setup the next timeout now so it doesn't drift */
+    /* due to processing the async probe code */
+    mod_timer(&timer, jiffies + val);
+
+    /* determine pt_regs from the kernel stack */
+    /* @todo This doesn't seem to get a reasonable pt_regs pointer */
+    /* based on the value of regs->eip. However, KSTK_EIP() in */
+    /* include/asm/processor.h implies regs->eip is valid... */
+    regs = task_pt_regs(current);
+
+    /* Call the asynchronous probe with a ptregs struct */
+    inst_async(regs);
+}
+
+/* called when the module loads. */
+int init_module(void)
+{
+    int ret;
+
+    TRANSPORT_OPEN;
+
+    addr = _stp_stat_init(HIST_LINEAR, 0, 1000, 100);
+
+    cur_addr = _stp_map_new_int64(1000, INT64);
+
+    /* register the os_timer */
+    init_timer(&timer);
+
+    timer.expires = jiffies + 50;
+    timer.function = os_timer_callback;
+
+    /* data is usd for defining when the next timeout shoud occur */
+    timer.data = 50;
+
+    add_timer(&timer);
+
+    ret = 0;
+
+    return ret;
+}
+
+static void probe_exit (void)
+{
+    /* unregister the os_timer */
+    del_timer_sync(&timer);
+
+    /* print out any colledted data, etc */
+    _stp_printf ("os timer done. Currently an issue with tast_pt_regs() call so data below may not be valid\n");
+    _stp_stat_print (addr, "addr: count:%C  sum:%S  avg:%A  min:%m  max:%M\n%H", 0);
+
+    _stp_map_print (cur_addr, "Count: %d\tInterrupts: %1P");
+    _stp_map_del(cur_addr);
+
+    _stp_print_flush();
+}
+
+/* required */
+void cleanup_module(void)
+{
+    _stp_transport_close();
+}
+
+MODULE_LICENSE("GPL");