acb65150a4
With the hardware TopDown metrics feature, sample-read feature should be supported for a topdown group, e.g., sample a non-topdown event and read a topdown metric group. But the current perf record code errors out. For a topdown metric group, the slots event must be the leader of the group, but the leader slots event doesn't support sampling. To support sample-read the topdown metric group, use the 2nd event of the group as the "leader" for the purposes of sampling. Only the platform with Topdown metic feature supports sample-read the topdown group. Add arch_topdown_sample_read() to indicate whether the topdown group supports sample-read. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Acked-by: Jiri Olsa <jolsa@redhat.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lore.kernel.org/lkml/20200911144808.27603-3-kan.liang@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
64 lines
1.2 KiB
C
64 lines
1.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <stdio.h>
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#include "api/fs/fs.h"
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#include "util/pmu.h"
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#include "util/topdown.h"
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/*
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* Check whether we can use a group for top down.
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* Without a group may get bad results due to multiplexing.
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*/
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bool arch_topdown_check_group(bool *warn)
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{
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int n;
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if (sysctl__read_int("kernel/nmi_watchdog", &n) < 0)
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return false;
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if (n > 0) {
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*warn = true;
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return false;
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}
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return true;
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}
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void arch_topdown_group_warn(void)
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{
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fprintf(stderr,
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"nmi_watchdog enabled with topdown. May give wrong results.\n"
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"Disable with echo 0 > /proc/sys/kernel/nmi_watchdog\n");
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}
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#define TOPDOWN_SLOTS 0x0400
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static bool is_topdown_slots_event(struct evsel *counter)
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{
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if (!counter->pmu_name)
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return false;
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if (strcmp(counter->pmu_name, "cpu"))
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return false;
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if (counter->core.attr.config == TOPDOWN_SLOTS)
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return true;
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return false;
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}
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/*
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* Check whether a topdown group supports sample-read.
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*
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* Only Topdown metic supports sample-read. The slots
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* event must be the leader of the topdown group.
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*/
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bool arch_topdown_sample_read(struct evsel *leader)
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{
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if (!pmu_have_event("cpu", "slots"))
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return false;
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if (is_topdown_slots_event(leader))
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return true;
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return false;
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}
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