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    SubjectRe: [PATCHSET 00/17] perf tools: Introduce new 'ftrace' command (v4)
    On 130813 11:20:52, Namhyung Kim wrote:
    > ------------8<-------------
    > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
    > index 9e78ec19caeb..10590b794cae 100644
    > --- a/tools/perf/builtin-ftrace.c
    > +++ b/tools/perf/builtin-ftrace.c
    > @@ -555,17 +555,25 @@ sleep:
    > while (true) {
    > int n = read(trace_fd, buf, sizeof(buf));
    >
    > - if (n < 0)
    > - goto out_close;
    > - if (n == 0)
    > + if (n < 0) {
    > + if (errno == EINTR || errno == EAGAIN)
    > + break;
    > + perror("flush read");
    > + goto out_close2;
    > + } else if (n == 0)
    > break;
    > - if (write(output_fd, buf, n) != n)
    > - goto out_close;
    > +
    > + if (write(output_fd, buf, n) != n) {
    > + perror("flush write");
    > + goto out_close2;
    > + }
    >
    > byte_written += n;
    > }
    > fra->state = RECORD_STATE__DONE;
    >
    > +out_close2:
    > + close(output_fd);
    > out_close:
    > close(trace_fd);
    > out:
    > @@ -579,6 +587,8 @@ out:
    > pthread_cond_signal(&recorder_ready_cond);
    > pthread_mutex_unlock(&recorder_mutex);
    > }
    > +
    > + pr_debug2("done with %ld bytes\n", (long)byte_written);
    > return fra;
    > }
    >

    Hmm, I already had hunk #3 in your git tree v4.

    > @@ -1139,12 +1149,12 @@ retry:
    > return record;
    > }
    >
    > - munmap(fra->map, pevent_get_page_size(ftrace->pevent));
    > - fra->map = NULL;
    > -
    > if (fra->done)
    > return NULL;
    >
    > + munmap(fra->map, pevent_get_page_size(ftrace->pevent));
    > + fra->map = NULL;
    > +
    > fra->offset += pevent_get_page_size(ftrace->pevent);
    > if (fra->offset >= fra->size) {
    > /* EOF */


    After patching your tree with just the first 2 hunks, I'm able to
    get ftrace-style function graphing out of perf.

    # ./perf ftrace record df
    Filesystem 1K-blocks Used Available Use% Mounted on
    <snip>...

    # ./perf --no-pager ftrace show | head -20
    overriding event (11) ftrace:funcgraph_entry with new print handler
    overriding event (10) ftrace:funcgraph_exit with new print handler
    2) 0.686 us | finish_task_switch();
    2) 0.260 us | finish_wait();
    2) | mutex_lock() {
    2) 0.211 us | _cond_resched();
    2) 1.170 us | }
    2) 0.319 us | generic_pipe_buf_confirm();
    2) 0.261 us | generic_pipe_buf_map();
    2) 0.129 us | generic_pipe_buf_unmap();
    2) 0.747 us | anon_pipe_buf_release();
    2) 0.138 us | mutex_unlock();
    2) | __wake_up_sync_key() {
    2) 0.279 us | _raw_spin_lock_irqsave();
    2) 0.135 us | __wake_up_common();
    2) 0.133 us | __lock_text_start();
    2) 3.386 us | }
    2) | kill_fasync() {
    2) | smp_reschedule_interrupt() {
    2) 0.130 us | kvm_guest_apic_eoi_write();

    Nice.

    Not sure if you intend to move all ftrace functionality over to
    perf ftrace, but the function graph timings is a great start and something sorely
    missing.

    Do you intend to add -e event support or -l function-specific options ? In the real
    world, without filtering on events or functions, I've had systems hang, plus
    performance impact is too great.

    A common invocation of ftrace via trace-cmd is:
    # trace-cmd record -p function_graph -e irq:* -l do_IRQ ping -c1 www.redhat.com

    So possible perf equivalent?
    # ./perf ftrace record -e irq:* -e do_IRQ ping -c1 www.redhat.com

    Thanks!


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