On Thu, Jan 22, 2009 at 1:45 PM, Kalle Valo <kalle.valo@xxxxxxxxx> wrote:
> When a directed tim bit is set, mac80211 currently disables power save
> ands sends a null frame to the AP. But if dynamic power save is
> disabled, mac80211 will not enable power save ever gain.
Why not?
Fix this by
> adding ps-poll functionality to mac80211. When a directed tim bit is
> set, mac80211 sends a ps-poll frame to the AP and checks for the more
> data bit in the returned data frames.
Still have to see the implementation but this sounds strange.
> Using ps-poll is slower than waking up with null frame, but it's saves more
> power in cases where the traffic is low. Userspace can control if either
> ps-poll or null wakeup method is used by enabling and disabling dynamic
> power save.
Do you have numbers how much power you save?. With PS-Poll you must
stay awak longer not saying that issueing TX (PS-poll) also consume
power.Ususally TXing has higher power consumption then RX.Instead of
tx(null PM=0) rx tx(ack)...rx tx(ack) tx(null PM=1) you have now
tx(ps-poll) rx tx (ack) tx(ps-poll) rx tx(ack). So if the AP holds
more then 3 packetes PS poll will consume more power in this very
simplified computation.
Do you measure power consumption on of the NIC or the whole system?
Thanks
Tomas
>
> Signed-off-by: Kalle Valo <kalle.valo@xxxxxxxxx>
> ---
>
> net/mac80211/ieee80211_i.h | 3 ++
> net/mac80211/mlme.c | 56 ++++++++++++++++++++++++++++++++++++++++++--
> net/mac80211/rx.c | 34 +++++++++++++++++++++++++++
> 3 files changed, 90 insertions(+), 3 deletions(-)
>
> diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
> index c9ffadb..76814e9 100644
> --- a/net/mac80211/ieee80211_i.h
> +++ b/net/mac80211/ieee80211_i.h
> @@ -710,6 +710,7 @@ struct ieee80211_local {
> unsigned int wmm_acm; /* bit field of ACM bits (BIT(802.1D tag)) */
>
> bool powersave;
> + bool pspolling;
> struct work_struct dynamic_ps_enable_work;
> struct work_struct dynamic_ps_disable_work;
> struct timer_list dynamic_ps_timer;
> @@ -902,6 +903,8 @@ u64 ieee80211_sta_get_rates(struct ieee80211_local *local,
> enum ieee80211_band band);
> void ieee80211_send_probe_req(struct ieee80211_sub_if_data *sdata, u8 *dst,
> u8 *ssid, size_t ssid_len);
> +void ieee80211_send_pspoll(struct ieee80211_local *local,
> + struct ieee80211_sub_if_data *sdata);
>
> /* scan/BSS handling */
> int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> index c7e61e2..26b3ed4 100644
> --- a/net/mac80211/mlme.c
> +++ b/net/mac80211/mlme.c
> @@ -475,6 +475,41 @@ static void ieee80211_send_deauth_disassoc(struct ieee80211_sub_if_data *sdata,
> ieee80211_tx_skb(sdata, skb, ifsta->flags & IEEE80211_STA_MFP_ENABLED);
> }
>
> +void ieee80211_send_pspoll(struct ieee80211_local *local,
> + struct ieee80211_sub_if_data *sdata)
> +{
> + struct ieee80211_if_sta *ifsta = &sdata->u.sta;
> + struct ieee80211_pspoll *pspoll;
> + struct sk_buff *skb;
> + u16 fc;
> +
> + skb = dev_alloc_skb(local->hw.extra_tx_headroom + sizeof(*pspoll));
> + if (!skb) {
> + printk(KERN_DEBUG "%s: failed to allocate buffer for "
> + "pspoll frame\n", sdata->dev->name);
> + return;
> + }
> + skb_reserve(skb, local->hw.extra_tx_headroom);
> +
> + pspoll = (struct ieee80211_pspoll *) skb_put(skb, sizeof(*pspoll));
> + memset(pspoll, 0, sizeof(*pspoll));
> + fc = IEEE80211_FTYPE_CTL | IEEE80211_STYPE_PSPOLL | IEEE80211_FCTL_PM;
> + pspoll->frame_control = cpu_to_le16(fc);
> + pspoll->aid = cpu_to_le16(ifsta->aid);
> +
> + /* aid in PS-Poll has its two MSBs each set to 1 */
> + pspoll->aid |= cpu_to_le16(1 << 15 | 1 << 14);
> +
> + memcpy(pspoll->bssid, ifsta->bssid, ETH_ALEN);
> + memcpy(pspoll->ta, sdata->dev->dev_addr, ETH_ALEN);
> +
> + printk(KERN_DEBUG "sending ps-poll");
> +
> + ieee80211_tx_skb(sdata, skb, 0);
> +
> + return;
> +}
> +
> /* MLME */
> static void ieee80211_sta_def_wmm_params(struct ieee80211_sub_if_data *sdata,
> struct ieee80211_bss *bss)
> @@ -1816,9 +1851,24 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
> directed_tim = ieee80211_check_tim(&elems, ifsta->aid);
>
> if (directed_tim) {
> - local->hw.conf.flags &= ~IEEE80211_CONF_PS;
> - ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
> - ieee80211_send_nullfunc(local, sdata, 0);
> + if (local->hw.conf.dynamic_ps_timeout > 0) {
> + local->hw.conf.flags &= ~IEEE80211_CONF_PS;
> + ieee80211_hw_config(local,
> + IEEE80211_CONF_CHANGE_PS);
> + ieee80211_send_nullfunc(local, sdata, 0);
> + } else {
> + local->pspolling = true;
> +
> + /*
> + * Here is assumed that the driver will be
> + * able to send ps-poll frame and receive a
> + * response even though power save mode is
> + * enabled, but some drivers might require
> + * to disable power save here. This needs
> + * to be investigated.
> + */
> + ieee80211_send_pspoll(local, sdata);
> + }
> }
> }
>
> diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
> index 9fd9d21..59b0a50 100644
> --- a/net/mac80211/rx.c
> +++ b/net/mac80211/rx.c
> @@ -740,6 +740,39 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
> return result;
> }
>
> +static ieee80211_rx_result debug_noinline
> +ieee80211_rx_h_check_more_data(struct ieee80211_rx_data *rx)
> +{
> + struct ieee80211_local *local;
> + struct ieee80211_hdr *hdr;
> + struct sk_buff *skb;
> +
> + local = rx->local;
> + skb = rx->skb;
> + hdr = (struct ieee80211_hdr *) skb->data;
> +
> + if (!local->pspolling)
> + return RX_CONTINUE;
> +
> + if (!ieee80211_has_fromds(hdr->frame_control))
> + /* this is not from AP */
> + return RX_CONTINUE;
> +
> + if (!ieee80211_is_data(hdr->frame_control))
> + return RX_CONTINUE;
> +
> + if (!ieee80211_has_moredata(hdr->frame_control)) {
> + /* AP has no more frames buffered for us */
> + local->pspolling = false;
> + return RX_CONTINUE;
> + }
> +
> + /* more data bit is set, let's request a new frame from the AP */
> + ieee80211_send_pspoll(local, rx->sdata);
> +
> + return RX_CONTINUE;
> +}
> +
> static void ap_sta_ps_start(struct sta_info *sta)
> {
> struct ieee80211_sub_if_data *sdata = sta->sdata;
> @@ -2006,6 +2039,7 @@ static void ieee80211_invoke_rx_handlers(struct ieee80211_sub_if_data *sdata,
> CALL_RXH(ieee80211_rx_h_passive_scan)
> CALL_RXH(ieee80211_rx_h_check)
> CALL_RXH(ieee80211_rx_h_decrypt)
> + CALL_RXH(ieee80211_rx_h_check_more_data)
> CALL_RXH(ieee80211_rx_h_sta_process)
> CALL_RXH(ieee80211_rx_h_defragment)
> CALL_RXH(ieee80211_rx_h_ps_poll)
>
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