81 lines
2.8 KiB
Diff
81 lines
2.8 KiB
Diff
From 5d45e3a5d2e2d929095489a37579c3b7fc059450 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= <philmd@redhat.com>
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Date: Tue, 3 Sep 2019 14:21:10 +0100
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Subject: [PATCH 1/8] trace: Clarify DTrace/SystemTap help message
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Philippe Mathieu-Daudé <philmd@redhat.com>
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Message-id: <20190903142110.25673-2-philmd@redhat.com>
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Patchwork-id: 90255
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O-Subject: [RHEL-AV-8.1.0 qemu-kvm PATCH 1/1] trace: Clarify DTrace/SystemTap help message
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Bugzilla: 1516220
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Peter Xu <peterx@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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Most tracing backends are implemented within QEMU, except the
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DTrace/SystemTap backends.
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One side effect is when running 'qemu -trace help', an incomplete
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list of trace events is displayed when using the DTrace/SystemTap
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backends.
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This is partly due to trace events registered as modules with
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trace_init(), and since the events are not used within QEMU,
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the linker optimize and remove the unused modules (which is
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OK in this particular case).
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Currently only the events compiled in trace-root.o and in the
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last trace.o member of libqemuutil.a are linked, resulting in
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an incomplete list of events.
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To avoid confusion, improve the help message, recommending to
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use the proper systemtap script to display the events list.
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Before:
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$ lm32-softmmu/qemu-system-lm32 -trace help 2>&1 | wc -l
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70
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After:
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$ lm32-softmmu/qemu-system-lm32 -trace help
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Run 'qemu-trace-stap list qemu-system-lm32' to print a list
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of names of trace points with the DTrace/SystemTap backends.
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$ qemu-trace-stap list qemu-system-lm32 | wc -l
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1136
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Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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Message-id: 20190823142203.5210-1-philmd@redhat.com
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Message-Id: <20190823142203.5210-1-philmd@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit 9f591a5d95e1969969632ab44cf35e505c8ddc3b)
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Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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trace/control.c | 6 ++++++
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1 file changed, 6 insertions(+)
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diff --git a/trace/control.c b/trace/control.c
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index 43fb786..d9cafc1 100644
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--- a/trace/control.c
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+++ b/trace/control.c
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@@ -165,6 +165,12 @@ void trace_list_events(void)
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while ((ev = trace_event_iter_next(&iter)) != NULL) {
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fprintf(stderr, "%s\n", trace_event_get_name(ev));
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}
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+#ifdef CONFIG_TRACE_DTRACE
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+ fprintf(stderr, "This list of names of trace points may be incomplete "
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+ "when using the DTrace/SystemTap backends.\n"
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+ "Run 'qemu-trace-stap list %s' to print the full list.\n",
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+ error_get_progname());
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+#endif
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}
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static void do_trace_enable_events(const char *line_buf)
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--
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1.8.3.1
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