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commit 7a6ae407b62615d3ffa9b0d2ac17771b7fc63056
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Author: Vince Weaver <vince@deater.net>
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Date: Thu Sep 27 23:47:58 2018 -0400
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perf_event: avoid floating point exception if running is 0
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The perf_event interface isn't supposed to return 0 for running, but
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it happens occasionally. So be sure not to divide by zero if this
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happens. This makes the rdpmc code match the generic perf code in this
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case.
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This is in response to bitbucket issue #52
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diff --git a/src/components/perf_event/perf_event.c b/src/components/perf_event/perf_event.c
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index 7fd753ed..82b7d398 100644
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--- a/src/components/perf_event/perf_event.c
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+++ b/src/components/perf_event/perf_event.c
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@@ -1099,14 +1099,23 @@ _pe_rdpmc_read( hwd_context_t *ctx, hwd_control_state_t *ctl,
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count = mmap_read_self(pe_ctl->events[i].mmap_buf,
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&enabled,&running);
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- /* TODO: error checking? */
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+ /* TODO: more error checking? */
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/* Handle multiplexing case */
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- if (enabled!=running) {
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+ if (enabled == running) {
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+ /* no adjustment needed */
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+ }
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+ else if (enabled && running) {
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adjusted = (enabled * 128LL) / running;
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adjusted = adjusted * count;
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adjusted = adjusted / 128LL;
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count = adjusted;
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+ } else {
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+ /* This should not happen, but we have had it reported */
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+ SUBDBG("perf_event kernel bug(?) count, enabled, "
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+ "running: %lld, %lld, %lld\n",
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+ papi_pe_buffer[0],enabled,running);
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+
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}
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pe_ctl->counts[i] = count;
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