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ec7a944360
Summary: We occasionally get write stalls (>1s Write() calls) on HDD under read load. The following timers explain almost all of the stalls: - perf_context.db_mutex_lock_nanos - perf_context.db_condition_wait_nanos - iostats_context.open_time - iostats_context.allocate_time - iostats_context.write_time - iostats_context.range_sync_time - iostats_context.logger_time In my experiments each of these occasionally takes >1s on write path under some workload. There are rare cases when Write() takes long but none of these takes long. Test Plan: Added code to our application to write the listed timings to log for slow writes. They usually add up to almost exactly the time Write() call took. Reviewers: rven, yhchiang, sdong Reviewed By: sdong Subscribers: march, dhruba, tnovak Differential Revision: https://reviews.facebook.net/D39177
47 lines
1.4 KiB
C++
47 lines
1.4 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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#pragma once
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#include "rocksdb/perf_context.h"
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#include "util/perf_step_timer.h"
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#include "util/stop_watch.h"
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namespace rocksdb {
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#if defined(NPERF_CONTEXT) || defined(IOS_CROSS_COMPILE)
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#define PERF_TIMER_GUARD(metric)
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#define PERF_TIMER_MEASURE(metric)
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#define PERF_TIMER_STOP(metric)
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#define PERF_TIMER_START(metric)
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#define PERF_COUNTER_ADD(metric, value)
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#else
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// Stop the timer and update the metric
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#define PERF_TIMER_STOP(metric) \
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perf_step_timer_ ## metric.Stop();
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#define PERF_TIMER_START(metric) \
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perf_step_timer_ ## metric.Start();
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// Declare and set start time of the timer
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#define PERF_TIMER_GUARD(metric) \
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PerfStepTimer perf_step_timer_ ## metric(&(perf_context.metric)); \
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perf_step_timer_ ## metric.Start();
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// Update metric with time elapsed since last START. start time is reset
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// to current timestamp.
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#define PERF_TIMER_MEASURE(metric) \
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perf_step_timer_ ## metric.Measure();
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// Increase metric value
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#define PERF_COUNTER_ADD(metric, value) \
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perf_context.metric += value;
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#endif
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}
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