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https://github.com/edk2-porting/linux-next.git
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12883efb67
Currently, the way the latency tracers and snapshot feature works is to have a separate trace_array called "max_tr" that holds the snapshot buffer. For latency tracers, this snapshot buffer is used to swap the running buffer with this buffer to save the current max latency. The only items needed for the max_tr is really just a copy of the buffer itself, the per_cpu data pointers, the time_start timestamp that states when the max latency was triggered, and the cpu that the max latency was triggered on. All other fields in trace_array are unused by the max_tr, making the max_tr mostly bloat. This change removes the max_tr completely, and adds a new structure called trace_buffer, that holds the buffer pointer, the per_cpu data pointers, the time_start timestamp, and the cpu where the latency occurred. The trace_array, now has two trace_buffers, one for the normal trace and one for the max trace or snapshot. By doing this, not only do we remove the bloat from the max_trace but the instances of traces can now use their own snapshot feature and not have just the top level global_trace have the snapshot feature and latency tracers for itself. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
136 lines
3.1 KiB
C
136 lines
3.1 KiB
C
/*
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* kdb helper for dumping the ftrace buffer
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*
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* Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com>
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*
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* ftrace_dump_buf based on ftrace_dump:
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
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*
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*/
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#include <linux/init.h>
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#include <linux/kgdb.h>
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#include <linux/kdb.h>
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#include <linux/ftrace.h>
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#include "trace.h"
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#include "trace_output.h"
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static void ftrace_dump_buf(int skip_lines, long cpu_file)
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{
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/* use static because iter can be a bit big for the stack */
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static struct trace_iterator iter;
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unsigned int old_userobj;
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int cnt = 0, cpu;
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trace_init_global_iter(&iter);
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for_each_tracing_cpu(cpu) {
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atomic_inc(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
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}
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old_userobj = trace_flags;
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/* don't look at user memory in panic mode */
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trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
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kdb_printf("Dumping ftrace buffer:\n");
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/* reset all but tr, trace, and overruns */
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memset(&iter.seq, 0,
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sizeof(struct trace_iterator) -
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offsetof(struct trace_iterator, seq));
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iter.iter_flags |= TRACE_FILE_LAT_FMT;
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iter.pos = -1;
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if (cpu_file == RING_BUFFER_ALL_CPUS) {
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for_each_tracing_cpu(cpu) {
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iter.buffer_iter[cpu] =
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ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu);
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ring_buffer_read_start(iter.buffer_iter[cpu]);
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tracing_iter_reset(&iter, cpu);
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}
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} else {
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iter.cpu_file = cpu_file;
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iter.buffer_iter[cpu_file] =
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ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu_file);
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ring_buffer_read_start(iter.buffer_iter[cpu_file]);
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tracing_iter_reset(&iter, cpu_file);
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}
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if (!trace_empty(&iter))
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trace_find_next_entry_inc(&iter);
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while (!trace_empty(&iter)) {
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if (!cnt)
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kdb_printf("---------------------------------\n");
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cnt++;
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if (trace_find_next_entry_inc(&iter) != NULL && !skip_lines)
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print_trace_line(&iter);
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if (!skip_lines)
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trace_printk_seq(&iter.seq);
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else
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skip_lines--;
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if (KDB_FLAG(CMD_INTERRUPT))
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goto out;
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}
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if (!cnt)
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kdb_printf(" (ftrace buffer empty)\n");
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else
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kdb_printf("---------------------------------\n");
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out:
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trace_flags = old_userobj;
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for_each_tracing_cpu(cpu) {
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atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
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}
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for_each_tracing_cpu(cpu)
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if (iter.buffer_iter[cpu])
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ring_buffer_read_finish(iter.buffer_iter[cpu]);
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}
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/*
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* kdb_ftdump - Dump the ftrace log buffer
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*/
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static int kdb_ftdump(int argc, const char **argv)
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{
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int skip_lines = 0;
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long cpu_file;
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char *cp;
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if (argc > 2)
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return KDB_ARGCOUNT;
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if (argc) {
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skip_lines = simple_strtol(argv[1], &cp, 0);
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if (*cp)
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skip_lines = 0;
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}
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if (argc == 2) {
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cpu_file = simple_strtol(argv[2], &cp, 0);
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if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 ||
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!cpu_online(cpu_file))
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return KDB_BADINT;
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} else {
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cpu_file = RING_BUFFER_ALL_CPUS;
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}
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kdb_trap_printk++;
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ftrace_dump_buf(skip_lines, cpu_file);
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kdb_trap_printk--;
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return 0;
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}
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static __init int kdb_ftrace_register(void)
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{
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kdb_register_repeat("ftdump", kdb_ftdump, "[skip_#lines] [cpu]",
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"Dump ftrace log", 0, KDB_REPEAT_NONE);
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return 0;
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}
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late_initcall(kdb_ftrace_register);
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