lkml.org 
[lkml]   [2020]   [Nov]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.4 143/158] mac80211: minstrel: remove deferred sampling code
    Date
    From: Felix Fietkau <nbd@nbd.name>

    commit 4fe40b8e1566dad04c87fbf299049a1d0d4bd58d upstream.

    Deferring sampling attempts to the second stage has some bad interactions
    with drivers that process the rate table in hardware and use the probe flag
    to indicate probing packets (e.g. most mt76 drivers). On affected drivers
    it can lead to probing not working at all.

    If the link conditions turn worse, it might not be such a good idea to
    do a lot of sampling for lower rates in this case.

    Fix this by simply skipping the sample attempt instead of deferring it,
    but keep the checks that would allow it to be sampled if it was skipped
    too often, but only if it has less than 95% success probability.

    Also ensure that IEEE80211_TX_CTL_RATE_CTRL_PROBE is set for all probing
    packets.

    Cc: stable@vger.kernel.org
    Fixes: cccf129f820e ("mac80211: add the 'minstrel' rate control algorithm")
    Signed-off-by: Felix Fietkau <nbd@nbd.name>
    Link: https://lore.kernel.org/r/20201111183359.43528-2-nbd@nbd.name
    Signed-off-by: Johannes Berg <johannes.berg@intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/mac80211/rc80211_minstrel.c | 25 ++++---------------------
    net/mac80211/rc80211_minstrel.h | 1 -
    2 files changed, 4 insertions(+), 22 deletions(-)

    --- a/net/mac80211/rc80211_minstrel.c
    +++ b/net/mac80211/rc80211_minstrel.c
    @@ -283,12 +283,6 @@ minstrel_tx_status(void *priv, struct ie
    mi->r[ndx].stats.success += success;
    }

    - if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
    - mi->sample_packets++;
    -
    - if (mi->sample_deferred > 0)
    - mi->sample_deferred--;
    -
    if (time_after(jiffies, mi->last_stats_update +
    (mp->update_interval * HZ) / 1000))
    minstrel_update_stats(mp, mi);
    @@ -363,7 +357,7 @@ minstrel_get_rate(void *priv, struct iee
    return;

    delta = (mi->total_packets * sampling_ratio / 100) -
    - (mi->sample_packets + mi->sample_deferred / 2);
    + mi->sample_packets;

    /* delta < 0: no sampling required */
    prev_sample = mi->prev_sample;
    @@ -372,7 +366,6 @@ minstrel_get_rate(void *priv, struct iee
    return;

    if (mi->total_packets >= 10000) {
    - mi->sample_deferred = 0;
    mi->sample_packets = 0;
    mi->total_packets = 0;
    } else if (delta > mi->n_rates * 2) {
    @@ -397,19 +390,8 @@ minstrel_get_rate(void *priv, struct iee
    * rate sampling method should be used.
    * Respect such rates that are not sampled for 20 interations.
    */
    - if (mrr_capable &&
    - msr->perfect_tx_time > mr->perfect_tx_time &&
    - msr->stats.sample_skipped < 20) {
    - /* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
    - * packets that have the sampling rate deferred to the
    - * second MRR stage. Increase the sample counter only
    - * if the deferred sample rate was actually used.
    - * Use the sample_deferred counter to make sure that
    - * the sampling is not done in large bursts */
    - info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
    - rate++;
    - mi->sample_deferred++;
    - } else {
    + if (msr->perfect_tx_time < mr->perfect_tx_time ||
    + msr->stats.sample_skipped >= 20) {
    if (!msr->sample_limit)
    return;

    @@ -429,6 +411,7 @@ minstrel_get_rate(void *priv, struct iee

    rate->idx = mi->r[ndx].rix;
    rate->count = minstrel_get_retry_count(&mi->r[ndx], info);
    + info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
    }


    --- a/net/mac80211/rc80211_minstrel.h
    +++ b/net/mac80211/rc80211_minstrel.h
    @@ -79,7 +79,6 @@ struct minstrel_sta_info {
    u8 max_prob_rate;
    unsigned int total_packets;
    unsigned int sample_packets;
    - int sample_deferred;

    unsigned int sample_row;
    unsigned int sample_column;

    \
     
     \ /
      Last update: 2020-11-23 14:09    [W:3.868 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site