#include <fcntl.h>
#include <stdlib.h>
#include <sys/param.h>
+#include <linux/futex.h>
+#include <sys/time.h>
#include <asm/timex.h> //for get_cycles()
alarm(3);
}
+/* Do a buffer switch. Don't switch if buffer is completely empty */
+static void flush_buffer(struct ltt_buf *ltt_buf)
+{
+
+
+}
+
+static inline int ltt_buffer_get(struct ltt_buf *ltt_buf,
+ unsigned int *offset)
+{
+ unsigned int consumed_old, consumed_idx;
+ consumed_old = atomic_read(<t_buf->consumed);
+ consumed_idx = SUBBUF_INDEX(consumed_old, ltt_buf);
+
+ if(atomic_read(<t_buf->commit_count[consumed_idx])
+ != atomic_read(<t_buf->reserve_count[consumed_idx])) {
+ return -EAGAIN;
+ }
+ if((SUBBUF_TRUNC(atomic_read(<t_buf->offset), ltt_buf)
+ -SUBBUF_TRUNC(consumed_old, ltt_buf)) == 0) {
+ return -EAGAIN;
+ }
+
+ *offset = consumed_old;
+
+ return 0;
+}
+
+static inline int ltt_buffer_put(struct ltt_buf *ltt_buf,
+ unsigned int offset)
+{
+ unsigned int consumed_old, consumed_new;
+ int ret;
+
+ consumed_old = offset;
+ consumed_new = SUBBUF_ALIGN(consumed_old, ltt_buf);
+ if(atomic_cmpxchg(<t_buf->consumed, consumed_old, consumed_new)
+ != consumed_old) {
+ /* We have been pushed by the writer : the last buffer read _is_
+ * corrupted!
+ * It can also happen if this is a buffer we never got. */
+ return -EIO;
+ } else {
+ if(atomic_read(<t_buf->full) == 1) {
+ /* tell the client that buffer is now unfull */
+ ret = futex(<t_buf->full, FUTEX_WAKE, 1, NULL, NULL, 0);
+ if(ret != 1) {
+ printf("LTT warning : race condition : writer not waiting or too many writers\n");
+ }
+ atomic_set(<t_buf->full, 0);
+ }
+ }
+}
+
+/* In the writer :
+ *
+ * if(buffer full condition) {
+ * put myself in the wait queue
+ * ltt_buf->full = 1;
+ * schedule
+ * }
+ *{
+ if(buffer_is_full) {
+ atomic_set(<t_buf->full, 1);
+ ret = futex(<t_buf->full, 1, NULL, NULL, 0);
+ }
+}
+
+ */
+
+static int read_subbuffer(struct ltt_buf *ltt_buf, int fd)
+{
+ int err;
+ printf("LTT read buffer\n");
+
+
+ err = ltt_buffer_get(&shared_trace_info->channel.cpu, &consumed_old);
+ if(err != -EAGAIN && err != 0) {
+ printf("LTT Reserving sub buffer failed\n");
+ goto get_error;
+ }
+
+ err = TEMP_FAILURE_RETRY(write(fd,
+ ltt_buf->start
+ + (consumed_old & ((ltt_buf->alloc_size)-1)),
+ ltt_buf->subbuf_size));
+
+ if(err < 0) {
+ perror("Error in writing to file");
+ goto write_error;
+ }
+#if 0
+ err = fsync(pair->trace);
+ if(err < 0) {
+ ret = errno;
+ perror("Error in writing to file");
+ goto write_error;
+ }
+#endif //0
+write_error:
+ err = ltt_buffer_put(&shared_trace_info->channel.cpu, consumed_old);
+
+ if(err != 0) {
+ if(err == -EIO) {
+ perror("Reader has been pushed by the writer, last subbuffer corrupted.");
+ /* FIXME : we may delete the last written buffer if we wish. */
+ }
+ goto get_error;
+ }
+
+get_error:
+ return err;
+}
/* This function is called by ltt_rw_init which has signals blocked */
static void ltt_usertrace_fast_daemon(struct ltt_trace_info *shared_trace_info,
if(traced_pid == 0) break; /* parent died */
if(parent_exited) break;
printf("LTT Doing a buffer switch read. pid is : %lu\n", getpid());
- //printf("Test parent. pid is : %lu, ppid is %lu\n", getpid(), getppid());
+
+ do {
+ ret = read_buffer(&shared_trace_info->channel.cpu, fd_cpu);
+ } while(ret == 0);
+
+ do {
+ ret = read_buffer(&shared_trace_info->channel.facilities, fd_fac);
+ } while(ret == 0);
}
/* Buffer force switch (flush) */
- //TODO
-
+ flush_buffer(&shared_trace_info->channel.cpu);
+ do {
+ ret = read_buffer(&shared_trace_info->channel.cpu, fd_cpu);
+ } while(ret == 0);
+
+
+ flush_buffer(&shared_trace_info->channel.facilities);
+ do {
+ ret = read_buffer(&shared_trace_info->channel.facilities, fd_fac);
+ } while(ret == 0);
+
close(fd_fac);
close(fd_cpu);
shared_trace_info = mmap(0, sizeof(*thread_trace_info),
PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, 0, 0);
memset(shared_trace_info, 0, sizeof(*shared_trace_info));
+ /* Tricky semaphore : is in a shared memory space, so it's ok for a fast
+ * mutex (futex). */
+ atomic_set(&shared_trace_info->channel.facilities.full, 0);
+ shared_trace_info->channel.facilities.alloc_size = LTT_BUF_SIZE_FACILITIES;
+ shared_trace_info->channel.facilities.subbuf_size = LTT_SUBBUF_SIZE_FACILITIES;
+ atomic_set(&shared_trace_info->channel.cpu.full, 0);
+ shared_trace_info->channel.cpu.alloc_size = LTT_BUF_SIZE_CPU;
+ shared_trace_info->channel.cpu.subbuf_size = LTT_SUBBUF_SIZE_CPU;
shared_trace_info->init = 1;
/* Disable signals */
#include <asm/atomic.h>
#include <pthread.h>
-#ifndef LTT_BUF_SIZE_CPU
-#define LTT_BUF_SIZE_CPU 1048576
+
+#ifndef LTT_N_SUBBUFS
+#define LTT_N_SUBBUFS 2
+#endif //LTT_N_SUBBUFS
+
+#ifndef LTT_SUBBUF_SIZE_CPU
+#define LTT_SUBBUF_SIZE_CPU 1048576
#endif //LTT_BUF_SIZE_CPU
-#ifndef LTT_BUF_SIZE_FACILITIES
-#define LTT_BUF_SIZE_FACILITIES 4096
+#define LTT_BUF_SIZE_CPU (LTT_SUBBUF_SIZE_CPU * LTT_N_SUBBUFS)
+
+#ifndef LTT_SUBBUF_SIZE_FACILITIES
+#define LTT_SUBBUF_SIZE_FACILITIES 4096
#endif //LTT_BUF_SIZE_FACILITIES
+#define LTT_BUF_SIZE_FACILITIES (LTT_SUBBUF_SIZE_FACILITIES * LTT_N_SUBBUFS)
+
#ifndef LTT_USERTRACE_ROOT
#define LTT_USERTRACE_ROOT "/tmp/ltt-usertrace"
#endif //LTT_USERTRACE_ROOT
+
+/* Buffer offset macros */
+
+#define BUFFER_OFFSET(offset, buf) (offset & (buf->alloc_size-1))
+#define SUBBUF_OFFSET(offset, buf) (offset & (buf->subbuf_size-1))
+#define SUBBUF_ALIGN(offset, buf) \
+ (((offset) + buf->subbuf_size) & (~(buf->subbuf_size-1)))
+#define SUBBUF_TRUNC(offset, buf) \
+ ((offset) & (~(buf->subbuf_size-1)))
+#define SUBBUF_INDEX(offset, buf) \
+ (BUFFER_OFFSET(offset,buf)/buf->subbuf_size)
+
+
struct ltt_buf {
atomic_t offset;
- atomic_t reserve_count;
- atomic_t commit_count;
+ atomic_t consumed;
+ atomic_t reserve_count[LTT_N_SUBBUFS];
+ atomic_t commit_count[LTT_N_SUBBUFS];
atomic_t events_lost;
+ atomic_t full; /* futex on which the writer waits : 1 : full */
+ unsigned int alloc_size;
+ unsigned int subbuf_size;
};
struct ltt_trace_info {
int init;
int filter;
-#ifndef LTT_USE_THREADS
pid_t daemon_id;
-#else
- pthread_t daemon_id;
-#endif //LTT_USE_THREADS
atomic_t nesting;
struct {
struct ltt_buf facilities;
projects / lttv.git / commitdiff
