80d55154b2
The biggest flaw in current minstrel_ht is the fact that it needs way too many probing packets to be able to quickly find the best rate. Depending on the wifi hardware and operating mode, this can significantly reduce throughput when not operating at the highest available data rate. In order to be able to significantly reduce the amount of rate sampling, we need a much smarter selection of probing rates. The new approach introduced by this patch maintains a limited set of available rates to be tested during a statistics window. They are split into distinct categories: - MINSTREL_SAMPLE_TYPE_INC - incremental rate upgrade: Pick the next rate group and find the first rate that is faster than the current max. throughput rate - MINSTREL_SAMPLE_TYPE_JUMP - random testing of higher rates: Pick a random rate from the next group that is faster than the current max throughput rate. This allows faster adaptation when the link changes significantly - MINSTREL_SAMPLE_TYPE_SLOW - test a rate between max_prob, max_tp2 and max_tp in order to reduce the gap between them In order to prioritize sampling, every 6 attempts are split into 3x INC, 2x JUMP, 1x SLOW. Available rates are checked and refilled on every stats window update. With this approach, we finally get a very small delta in throughput when comparing setting the optimal data rate as a fixed rate vs normal rate control operation. Signed-off-by: Felix Fietkau <nbd@nbd.name> Link: https://lore.kernel.org/r/20210127055735.78599-4-nbd@nbd.name Signed-off-by: Johannes Berg <johannes.berg@intel.com>
215 lines
5.3 KiB
C
215 lines
5.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
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*/
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#ifndef __RC_MINSTREL_HT_H
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#define __RC_MINSTREL_HT_H
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#include <linux/bitfield.h>
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/* number of highest throughput rates to consider*/
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#define MAX_THR_RATES 4
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#define SAMPLE_COLUMNS 10 /* number of columns in sample table */
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/* scaled fraction values */
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#define MINSTREL_SCALE 12
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#define MINSTREL_FRAC(val, div) (((val) << MINSTREL_SCALE) / div)
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#define MINSTREL_TRUNC(val) ((val) >> MINSTREL_SCALE)
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#define EWMA_LEVEL 96 /* ewma weighting factor [/EWMA_DIV] */
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#define EWMA_DIV 128
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/*
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* Coefficients for moving average with noise filter (period=16),
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* scaled by 10 bits
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*
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* a1 = exp(-pi * sqrt(2) / period)
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* coeff2 = 2 * a1 * cos(sqrt(2) * 2 * pi / period)
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* coeff3 = -sqr(a1)
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* coeff1 = 1 - coeff2 - coeff3
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*/
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#define MINSTREL_AVG_COEFF1 (MINSTREL_FRAC(1, 1) - \
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MINSTREL_AVG_COEFF2 - \
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MINSTREL_AVG_COEFF3)
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#define MINSTREL_AVG_COEFF2 0x00001499
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#define MINSTREL_AVG_COEFF3 -0x0000092e
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/*
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* The number of streams can be changed to 2 to reduce code
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* size and memory footprint.
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*/
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#define MINSTREL_MAX_STREAMS 4
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#define MINSTREL_HT_STREAM_GROUPS 4 /* BW(=2) * SGI(=2) */
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#define MINSTREL_VHT_STREAM_GROUPS 6 /* BW(=3) * SGI(=2) */
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#define MINSTREL_HT_GROUPS_NB (MINSTREL_MAX_STREAMS * \
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MINSTREL_HT_STREAM_GROUPS)
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#define MINSTREL_VHT_GROUPS_NB (MINSTREL_MAX_STREAMS * \
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MINSTREL_VHT_STREAM_GROUPS)
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#define MINSTREL_LEGACY_GROUPS_NB 2
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#define MINSTREL_GROUPS_NB (MINSTREL_HT_GROUPS_NB + \
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MINSTREL_VHT_GROUPS_NB + \
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MINSTREL_LEGACY_GROUPS_NB)
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#define MINSTREL_HT_GROUP_0 0
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#define MINSTREL_CCK_GROUP (MINSTREL_HT_GROUP_0 + MINSTREL_HT_GROUPS_NB)
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#define MINSTREL_OFDM_GROUP (MINSTREL_CCK_GROUP + 1)
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#define MINSTREL_VHT_GROUP_0 (MINSTREL_OFDM_GROUP + 1)
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#define MCS_GROUP_RATES 10
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#define MI_RATE_IDX_MASK GENMASK(3, 0)
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#define MI_RATE_GROUP_MASK GENMASK(15, 4)
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#define MI_RATE(_group, _idx) \
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(FIELD_PREP(MI_RATE_GROUP_MASK, _group) | \
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FIELD_PREP(MI_RATE_IDX_MASK, _idx))
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#define MI_RATE_IDX(_rate) FIELD_GET(MI_RATE_IDX_MASK, _rate)
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#define MI_RATE_GROUP(_rate) FIELD_GET(MI_RATE_GROUP_MASK, _rate)
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#define MINSTREL_SAMPLE_RATES 5 /* rates per sample type */
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#define MINSTREL_SAMPLE_INTERVAL (HZ / 50)
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struct minstrel_priv {
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struct ieee80211_hw *hw;
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bool has_mrr;
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u32 sample_switch;
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unsigned int cw_min;
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unsigned int cw_max;
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unsigned int max_retry;
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unsigned int segment_size;
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unsigned int update_interval;
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u8 cck_rates[4];
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u8 ofdm_rates[NUM_NL80211_BANDS][8];
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#ifdef CONFIG_MAC80211_DEBUGFS
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/*
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* enable fixed rate processing per RC
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* - write static index to debugfs:ieee80211/phyX/rc/fixed_rate_idx
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* - write -1 to enable RC processing again
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* - setting will be applied on next update
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*/
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u32 fixed_rate_idx;
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#endif
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};
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struct mcs_group {
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u16 flags;
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u8 streams;
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u8 shift;
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u8 bw;
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u16 duration[MCS_GROUP_RATES];
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};
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extern const s16 minstrel_cck_bitrates[4];
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extern const s16 minstrel_ofdm_bitrates[8];
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extern const struct mcs_group minstrel_mcs_groups[];
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struct minstrel_rate_stats {
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/* current / last sampling period attempts/success counters */
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u16 attempts, last_attempts;
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u16 success, last_success;
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/* total attempts/success counters */
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u32 att_hist, succ_hist;
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/* prob_avg - moving average of prob */
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u16 prob_avg;
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u16 prob_avg_1;
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/* maximum retry counts */
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u8 retry_count;
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u8 retry_count_rtscts;
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bool retry_updated;
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};
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enum minstrel_sample_type {
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MINSTREL_SAMPLE_TYPE_INC,
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MINSTREL_SAMPLE_TYPE_JUMP,
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MINSTREL_SAMPLE_TYPE_SLOW,
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__MINSTREL_SAMPLE_TYPE_MAX
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};
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struct minstrel_mcs_group_data {
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u8 index;
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u8 column;
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/* sorted rate set within a MCS group*/
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u16 max_group_tp_rate[MAX_THR_RATES];
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u16 max_group_prob_rate;
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/* MCS rate statistics */
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struct minstrel_rate_stats rates[MCS_GROUP_RATES];
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};
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enum minstrel_sample_mode {
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MINSTREL_SAMPLE_IDLE,
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MINSTREL_SAMPLE_ACTIVE,
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MINSTREL_SAMPLE_PENDING,
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};
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struct minstrel_sample_category {
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u8 sample_group;
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u16 sample_rates[MINSTREL_SAMPLE_RATES];
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u16 cur_sample_rates[MINSTREL_SAMPLE_RATES];
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};
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struct minstrel_ht_sta {
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struct ieee80211_sta *sta;
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/* ampdu length (average, per sampling interval) */
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unsigned int ampdu_len;
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unsigned int ampdu_packets;
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/* ampdu length (EWMA) */
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unsigned int avg_ampdu_len;
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/* overall sorted rate set */
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u16 max_tp_rate[MAX_THR_RATES];
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u16 max_prob_rate;
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/* time of last status update */
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unsigned long last_stats_update;
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/* overhead time in usec for each frame */
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unsigned int overhead;
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unsigned int overhead_rtscts;
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unsigned int overhead_legacy;
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unsigned int overhead_legacy_rtscts;
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unsigned int total_packets_last;
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unsigned int total_packets_cur;
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unsigned int total_packets;
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unsigned int sample_packets;
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/* tx flags to add for frames for this sta */
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u32 tx_flags;
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unsigned long sample_time;
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struct minstrel_sample_category sample[__MINSTREL_SAMPLE_TYPE_MAX];
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u8 sample_seq;
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enum minstrel_sample_mode sample_mode;
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u16 sample_rate;
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u8 band;
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/* Bitfield of supported MCS rates of all groups */
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u16 supported[MINSTREL_GROUPS_NB];
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/* MCS rate group info and statistics */
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struct minstrel_mcs_group_data groups[MINSTREL_GROUPS_NB];
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};
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void minstrel_ht_add_sta_debugfs(void *priv, void *priv_sta, struct dentry *dir);
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int minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate,
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int prob_avg);
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#endif
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