From 374920cb0512f5938fdf1f5af4f9afa7502dd0f9 Mon Sep 17 00:00:00 2001 From: Daniel Halperin Date: Wed, 16 Mar 2011 19:16:36 -0700 Subject: [PATCH] iwlwifi: limit number of attempts for highest HT rate When filling out its rate scale table, iwlwifi repeats the first HT rate IWL_HT_NUMBER_TRY times. The hardware scheduler will stop using aggregation for any frame that fails LINK_QUAL_AGG_DISABLE_START_DEF times. Currently, both these constants equal 3. If iwlwifi probes a faster rate than the link supports, all frames in a (potentially tens of frames large) batch will fail IWL_HT_NUMBER_TRY times. Because this happens to be as large as LINK_QUAL_AGG_DISABLE_START_DEF, all frames will then be sent individually. This leads to a short, but performance-degrading window where the legacy stop-and-wait MAC takes over. Bounding the initial rate by (LINK_QUAL_AGG_DISABLE_START_DEF-1) attempts makes the third try use a lower rate and hence more be likely to succeed. This somewhat mitigates the above described behavior. Signed-off-by: Daniel Halperin Signed-off-by: Wey-Yi Guy --- drivers/net/wireless/iwlwifi/iwl-agn-rs.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-rs.c b/drivers/net/wireless/iwlwifi/iwl-agn-rs.c index d03b4734c89..63b58ecb0dc 100644 --- a/drivers/net/wireless/iwlwifi/iwl-agn-rs.c +++ b/drivers/net/wireless/iwlwifi/iwl-agn-rs.c @@ -2912,7 +2912,8 @@ static void rs_fill_link_cmd(struct iwl_priv *priv, ant_toggle_cnt = 1; repeat_rate = IWL_NUMBER_TRY; } else { - repeat_rate = IWL_HT_NUMBER_TRY; + repeat_rate = min(IWL_HT_NUMBER_TRY, + LINK_QUAL_AGG_DISABLE_START_DEF - 1); } lq_cmd->general_params.mimo_delimiter = -- 2.39.2