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authorDaniel Halperin <dhalperi@cs.washington.edu>2011-03-17 05:16:36 +0300
committerWey-Yi Guy <wey-yi.w.guy@intel.com>2011-03-25 16:57:50 +0300
commit374920cb0512f5938fdf1f5af4f9afa7502dd0f9 (patch)
tree8de1e768991818253240181ad4814d89ed2cd434 /drivers/net/wireless/iwlwifi/iwl-agn-rs.c
parentc8823ec1337017e23b99fb0814e2f3d62537f811 (diff)
downloadlinux-374920cb0512f5938fdf1f5af4f9afa7502dd0f9.tar.xz
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 <dhalperi@cs.washington.edu> Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Diffstat (limited to 'drivers/net/wireless/iwlwifi/iwl-agn-rs.c')
-rw-r--r--drivers/net/wireless/iwlwifi/iwl-agn-rs.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-rs.c b/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
index d03b4734c892..63b58ecb0dc6 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 =