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a9c0602149
In case redis starts and find that THP is enabled ("always"), instead
of printing a log message, which might go unnoticed, redis will try to
disable it (just for the redis process).
Note: it looks like on self-bulit kernels THP is likely be set to "always" by default.
Some discuss about THP side effect on Linux:
according to http://www.antirez.com/news/84, we can see that
redis latency spikes are caused by linux kernel THP feature.
I have tested on E3-2650 v3, and found that 2M huge page costs
about 0.25ms to fix COW page fault.
Add a new config 'disable-thp', the recommended setting is 'yes',
(default) the redis tries to disable THP by prctl syscall. But
users who really want THP can set it to "no"
Thanks to Oran & Yossi for suggestions.
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
95 lines
3.8 KiB
C
95 lines
3.8 KiB
C
/* latency.h -- latency monitor API header file
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* See latency.c for more information.
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*
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* ----------------------------------------------------------------------------
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*
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* Copyright (c) 2014, Salvatore Sanfilippo <antirez at gmail dot com>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of Redis nor the names of its contributors may be used
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* to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef __LATENCY_H
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#define __LATENCY_H
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#define LATENCY_TS_LEN 160 /* History length for every monitored event. */
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/* Representation of a latency sample: the sampling time and the latency
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* observed in milliseconds. */
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struct latencySample {
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int32_t time; /* We don't use time_t to force 4 bytes usage everywhere. */
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uint32_t latency; /* Latency in milliseconds. */
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};
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/* The latency time series for a given event. */
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struct latencyTimeSeries {
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int idx; /* Index of the next sample to store. */
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uint32_t max; /* Max latency observed for this event. */
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struct latencySample samples[LATENCY_TS_LEN]; /* Latest history. */
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};
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/* Latency statistics structure. */
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struct latencyStats {
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uint32_t all_time_high; /* Absolute max observed since latest reset. */
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uint32_t avg; /* Average of current samples. */
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uint32_t min; /* Min of current samples. */
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uint32_t max; /* Max of current samples. */
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uint32_t mad; /* Mean absolute deviation. */
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uint32_t samples; /* Number of non-zero samples. */
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time_t period; /* Number of seconds since first event and now. */
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};
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void latencyMonitorInit(void);
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void latencyAddSample(const char *event, mstime_t latency);
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int THPIsEnabled(void);
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int THPDisable(void);
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/* Latency monitoring macros. */
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/* Start monitoring an event. We just set the current time. */
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#define latencyStartMonitor(var) if (server.latency_monitor_threshold) { \
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var = mstime(); \
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} else { \
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var = 0; \
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}
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/* End monitoring an event, compute the difference with the current time
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* to check the amount of time elapsed. */
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#define latencyEndMonitor(var) if (server.latency_monitor_threshold) { \
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var = mstime() - var; \
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}
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/* Add the sample only if the elapsed time is >= to the configured threshold. */
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#define latencyAddSampleIfNeeded(event,var) \
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if (server.latency_monitor_threshold && \
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(var) >= server.latency_monitor_threshold) \
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latencyAddSample((event),(var));
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/* Remove time from a nested event. */
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#define latencyRemoveNestedEvent(event_var,nested_var) \
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event_var += nested_var;
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#endif /* __LATENCY_H */
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