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Date: Tue, 25 Sep 2012 13:48:42 -0700
From: David Sharp <dhsharp@...gle.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-kernel@...r.kernel.org,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Subject: Re: [PATCH v3 3/3] tracing: format non-nanosec times from tsc clock
without a decimal point.
On Mon, Sep 24, 2012 at 8:27 PM, Steven Rostedt <rostedt@...dmis.org> wrote:
> On Thu, 2012-09-20 at 15:52 -0700, David Sharp wrote:
>> With the addition of the "tsc" clock, formatting timestamps to look like
>> fractional seconds is misleading. Mark clocks as either in nanoseconds or
>> not, and format non-nanosecond timestamps as decimal integers.
>
> I got this:
>
> /work/autotest/nobackup/linux-test.git/kernel/trace/trace_output.c:636: undefined reference to `__umoddi3'
> /work/autotest/nobackup/linux-test.git/kernel/trace/trace_output.c:636: undefined reference to `__udivdi3'
> /work/autotest/nobackup/linux-test.git/kernel/trace/trace_output.c:636: undefined reference to `__umoddi3'
> /work/autotest/nobackup/linux-test.git/kernel/trace/trace_output.c:636: undefined reference to `__umoddi3'
> /work/autotest/nobackup/linux-test.git/kernel/trace/trace_output.c:636: undefined reference to `__udivdi3'
> /work/autotest/nobackup/linux-test.git/kernel/trace/trace_output.c:636: undefined reference to `__umoddi3'
> /work/autotest/nobackup/linux-test.git/kernel/trace/trace_output.c:636: undefined reference to `__udivdi3'
>
> when building for x86_32.
>
>> + int ret;
>> + struct trace_seq *s = &iter->seq;
>> + unsigned long verbose = trace_flags & TRACE_ITER_VERBOSE;
>> + unsigned long in_ns = iter->iter_flags & TRACE_FILE_TIME_IN_NS;
>> + unsigned long long abs_ts = iter->ts - iter->tr->time_start;
>> + unsigned long long rel_ts = next_ts - iter->ts;
>> + unsigned long mark_thresh;
>> +
>> + if (in_ns) {
>> + abs_ts = ns2usecs(abs_ts);
>> + rel_ts = ns2usecs(rel_ts);
>> + mark_thresh = preempt_mark_thresh_us;
>> + } else
>> + mark_thresh = preempt_mark_thresh_cycles;
>> +
>> + if (verbose && in_ns) {
>> + ret = trace_seq_printf(
>> + s, "[%08llx] %lld.%03lldms (+%lld.%03lldms): ",
>> + ns2usecs(iter->ts),
>> + abs_ts / USEC_PER_MSEC,
>> + abs_ts % USEC_PER_MSEC,
>> + rel_ts / USEC_PER_MSEC,
>
> You can't divide 64 bit numbers in the kernel. It breaks on 32bit archs.
I didn't realize that. Sorry. Not sure why I changed them to long long
in the first place.
Although, that does mean that it is currently overflowing every 4.29
seconds. I may as well fix that.
>
> -- Steve
>
>> + rel_ts % USEC_PER_MSEC);
>> + } else if (verbose && !in_ns) {
>> + ret = trace_seq_printf(
>> + s, "[%016llx] %lld (+%lld): ",
>> + iter->ts, abs_ts, rel_ts);
>> + } else { /* !verbose */
>> + ret = trace_seq_printf(
>> + s, " %4lld%s%c: ",
>> + abs_ts,
>> + in_ns ? "us" : "",
>> + rel_ts > mark_thresh ? '!' :
>> + rel_ts > 1 ? '+' : ' ');
>> + }
>> + return ret;
>> }
>>
>> int trace_print_context(struct trace_iterator *iter)
>> {
>> struct trace_seq *s = &iter->seq;
>> struct trace_entry *entry = iter->ent;
>> - unsigned long long t = ns2usecs(iter->ts);
>> - unsigned long usec_rem = do_div(t, USEC_PER_SEC);
>> - unsigned long secs = (unsigned long)t;
>> + unsigned long long t;
>> + unsigned long secs, usec_rem;
>> char comm[TASK_COMM_LEN];
>> int ret;
>>
>> @@ -644,8 +677,13 @@ int trace_print_context(struct trace_iterator *iter)
>> return 0;
>> }
>>
>> - return trace_seq_printf(s, " %5lu.%06lu: ",
>> - secs, usec_rem);
>> + if (iter->iter_flags & TRACE_FILE_TIME_IN_NS) {
>> + t = ns2usecs(iter->ts);
>> + usec_rem = do_div(t, USEC_PER_SEC);
>> + secs = (unsigned long)t;
>> + return trace_seq_printf(s, "%5lu.%06lu: ", secs, usec_rem);
>> + } else
>> + return trace_seq_printf(s, "%12llu: ", iter->ts);
>> }
>>
>> int trace_print_lat_context(struct trace_iterator *iter)
>> @@ -659,36 +697,30 @@ int trace_print_lat_context(struct trace_iterator *iter)
>> *next_entry = trace_find_next_entry(iter, NULL,
>> &next_ts);
>> unsigned long verbose = (trace_flags & TRACE_ITER_VERBOSE);
>> - unsigned long abs_usecs = ns2usecs(iter->ts - iter->tr->time_start);
>> - unsigned long rel_usecs;
>> +
>>
>> /* Restore the original ent_size */
>> iter->ent_size = ent_size;
>>
>> if (!next_entry)
>> next_ts = iter->ts;
>> - rel_usecs = ns2usecs(next_ts - iter->ts);
>>
>> if (verbose) {
>> char comm[TASK_COMM_LEN];
>>
>> trace_find_cmdline(entry->pid, comm);
>>
>> - ret = trace_seq_printf(s, "%16s %5d %3d %d %08x %08lx [%08llx]"
>> - " %ld.%03ldms (+%ld.%03ldms): ", comm,
>> - entry->pid, iter->cpu, entry->flags,
>> - entry->preempt_count, iter->idx,
>> - ns2usecs(iter->ts),
>> - abs_usecs / USEC_PER_MSEC,
>> - abs_usecs % USEC_PER_MSEC,
>> - rel_usecs / USEC_PER_MSEC,
>> - rel_usecs % USEC_PER_MSEC);
>> + ret = trace_seq_printf(
>> + s, "%16s %5d %3d %d %08x %08lx ",
>> + comm, entry->pid, iter->cpu, entry->flags,
>> + entry->preempt_count, iter->idx);
>> } else {
>> ret = lat_print_generic(s, entry, iter->cpu);
>> - if (ret)
>> - ret = lat_print_timestamp(s, abs_usecs, rel_usecs);
>> }
>>
>> + if (ret)
>> + ret = lat_print_timestamp(iter, next_ts);
>> +
>> return ret;
>> }
>>
>
>
--
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