* [PATCH] mac80211: adapt slot time in IBSS mode
@ 2012-12-03 21:21 Simon Wunderlich
2012-12-03 23:00 ` Julian Calaby
2012-12-04 14:54 ` Johannes Berg
0 siblings, 2 replies; 6+ messages in thread
From: Simon Wunderlich @ 2012-12-03 21:21 UTC (permalink / raw)
To: linux-wireless; +Cc: linville, johannes, Simon Wunderlich, Mathias Kretschmer
In 5GHz/802.11a, we are allowed to use short slot times. Doing this
may increases performance by 20% for legacy connections (54 MBit/s).
I can confirm this in my tests (27% more throughput using iperf), and
also have a small positive effect (5% more throughput) for HT rates,
tested on 1 stream.
Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
---
net/mac80211/ibss.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index fa862b2..1a5d29c 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -201,6 +201,19 @@ static void __ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
bss_change |= BSS_CHANGED_BASIC_RATES;
bss_change |= BSS_CHANGED_HT;
bss_change |= BSS_CHANGED_IBSS;
+
+ /* In 5 GHz/802.11a, we can always use short slot time.
+ * (IEEE 802.11-2012 18.3.8.7)
+ *
+ * In 2.4GHz, we must always use long slots in IBSS for compatibility
+ * reasons.
+ * (IEEE 802.11-2012 19.4.5)
+ *
+ * HT follows these specifications (IEEE 802.11-2012 20.3.18)
+ */
+ sdata->vif.bss_conf.use_short_slot = chan->band == IEEE80211_BAND_5GHZ;
+ bss_change |= BSS_CHANGED_ERP_SLOT;
+
sdata->vif.bss_conf.ibss_joined = true;
sdata->vif.bss_conf.ibss_creator = creator;
ieee80211_bss_info_change_notify(sdata, bss_change);
--
1.7.10.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] mac80211: adapt slot time in IBSS mode
2012-12-03 21:21 [PATCH] mac80211: adapt slot time in IBSS mode Simon Wunderlich
@ 2012-12-03 23:00 ` Julian Calaby
2012-12-04 8:08 ` Nicolas Cavallari
2012-12-04 10:42 ` Simon Wunderlich
2012-12-04 14:54 ` Johannes Berg
1 sibling, 2 replies; 6+ messages in thread
From: Julian Calaby @ 2012-12-03 23:00 UTC (permalink / raw)
To: Simon Wunderlich
Cc: linux-wireless, linville, johannes, Simon Wunderlich,
Mathias Kretschmer
Hi Simon,
On Tue, Dec 4, 2012 at 8:21 AM, Simon Wunderlich
<simon.wunderlich@s2003.tu-chemnitz.de> wrote:
> In 5GHz/802.11a, we are allowed to use short slot times. Doing this
> may increases performance by 20% for legacy connections (54 MBit/s).
> I can confirm this in my tests (27% more throughput using iperf), and
> also have a small positive effect (5% more throughput) for HT rates,
> tested on 1 stream.
>
> Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
> Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
> ---
> net/mac80211/ibss.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
> index fa862b2..1a5d29c 100644
> --- a/net/mac80211/ibss.c
> +++ b/net/mac80211/ibss.c
> @@ -201,6 +201,19 @@ static void __ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
> bss_change |= BSS_CHANGED_BASIC_RATES;
> bss_change |= BSS_CHANGED_HT;
> bss_change |= BSS_CHANGED_IBSS;
> +
> + /* In 5 GHz/802.11a, we can always use short slot time.
> + * (IEEE 802.11-2012 18.3.8.7)
> + *
> + * In 2.4GHz, we must always use long slots in IBSS for compatibility
> + * reasons.
> + * (IEEE 802.11-2012 19.4.5)
> + *
> + * HT follows these specifications (IEEE 802.11-2012 20.3.18)
> + */
> + sdata->vif.bss_conf.use_short_slot = chan->band == IEEE80211_BAND_5GHZ;
> + bss_change |= BSS_CHANGED_ERP_SLOT;
> +
I don't know if this is done elsewhere, but this code doesn't match
the comment - there is no test for IBSS mode.
Thanks,
--
Julian Calaby
Email: julian.calaby@gmail.com
Profile: http://www.google.com/profiles/julian.calaby/
.Plan: http://sites.google.com/site/juliancalaby/
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mac80211: adapt slot time in IBSS mode
2012-12-03 23:00 ` Julian Calaby
@ 2012-12-04 8:08 ` Nicolas Cavallari
2012-12-04 22:07 ` Julian Calaby
2012-12-04 10:42 ` Simon Wunderlich
1 sibling, 1 reply; 6+ messages in thread
From: Nicolas Cavallari @ 2012-12-04 8:08 UTC (permalink / raw)
To: Julian Calaby
Cc: Simon Wunderlich, linux-wireless, linville, johannes,
Simon Wunderlich, Mathias Kretschmer
On 04/12/2012 00:00, Julian Calaby wrote:
> Hi Simon,
>
> On Tue, Dec 4, 2012 at 8:21 AM, Simon Wunderlich
> <simon.wunderlich@s2003.tu-chemnitz.de> wrote:
>> In 5GHz/802.11a, we are allowed to use short slot times. Doing this
>> may increases performance by 20% for legacy connections (54 MBit/s).
>> I can confirm this in my tests (27% more throughput using iperf), and
>> also have a small positive effect (5% more throughput) for HT rates,
>> tested on 1 stream.
>>
>> Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
>> Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
>> ---
>> net/mac80211/ibss.c | 13 +++++++++++++
>> 1 file changed, 13 insertions(+)
>>
>> diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
>> index fa862b2..1a5d29c 100644
>> --- a/net/mac80211/ibss.c
>> +++ b/net/mac80211/ibss.c
>> @@ -201,6 +201,19 @@ static void __ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
>> bss_change |= BSS_CHANGED_BASIC_RATES;
>> bss_change |= BSS_CHANGED_HT;
>> bss_change |= BSS_CHANGED_IBSS;
>> +
>> + /* In 5 GHz/802.11a, we can always use short slot time.
>> + * (IEEE 802.11-2012 18.3.8.7)
>> + *
>> + * In 2.4GHz, we must always use long slots in IBSS for compatibility
>> + * reasons.
>> + * (IEEE 802.11-2012 19.4.5)
>> + *
>> + * HT follows these specifications (IEEE 802.11-2012 20.3.18)
>> + */
>> + sdata->vif.bss_conf.use_short_slot = chan->band == IEEE80211_BAND_5GHZ;
>> + bss_change |= BSS_CHANGED_ERP_SLOT;
>> +
>
> I don't know if this is done elsewhere, but this code doesn't match
> the comment - there is no test for IBSS mode.
>
> Thanks,
>
Do you happen to know any code path that calls
__ieee80211_sta_join_ibss() without being in IBSS mode ?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mac80211: adapt slot time in IBSS mode
2012-12-04 8:08 ` Nicolas Cavallari
@ 2012-12-04 22:07 ` Julian Calaby
0 siblings, 0 replies; 6+ messages in thread
From: Julian Calaby @ 2012-12-04 22:07 UTC (permalink / raw)
To: Nicolas Cavallari
Cc: Simon Wunderlich, linux-wireless, linville, johannes,
Simon Wunderlich, Mathias Kretschmer
Hi Nicolas,
On Tue, Dec 4, 2012 at 7:08 PM, Nicolas Cavallari
<Nicolas.Cavallari@lri.fr> wrote:
> On 04/12/2012 00:00, Julian Calaby wrote:
>> Hi Simon,
>>
>> On Tue, Dec 4, 2012 at 8:21 AM, Simon Wunderlich
>> <simon.wunderlich@s2003.tu-chemnitz.de> wrote:
>>> In 5GHz/802.11a, we are allowed to use short slot times. Doing this
>>> may increases performance by 20% for legacy connections (54 MBit/s).
>>> I can confirm this in my tests (27% more throughput using iperf), and
>>> also have a small positive effect (5% more throughput) for HT rates,
>>> tested on 1 stream.
>>>
>>> Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
>>> Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
>>> ---
>>> net/mac80211/ibss.c | 13 +++++++++++++
>>> 1 file changed, 13 insertions(+)
>>>
>>> diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
>>> index fa862b2..1a5d29c 100644
>>> --- a/net/mac80211/ibss.c
>>> +++ b/net/mac80211/ibss.c
>>> @@ -201,6 +201,19 @@ static void __ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
>>> bss_change |= BSS_CHANGED_BASIC_RATES;
>>> bss_change |= BSS_CHANGED_HT;
>>> bss_change |= BSS_CHANGED_IBSS;
>>> +
>>> + /* In 5 GHz/802.11a, we can always use short slot time.
>>> + * (IEEE 802.11-2012 18.3.8.7)
>>> + *
>>> + * In 2.4GHz, we must always use long slots in IBSS for compatibility
>>> + * reasons.
>>> + * (IEEE 802.11-2012 19.4.5)
>>> + *
>>> + * HT follows these specifications (IEEE 802.11-2012 20.3.18)
>>> + */
>>> + sdata->vif.bss_conf.use_short_slot = chan->band == IEEE80211_BAND_5GHZ;
>>> + bss_change |= BSS_CHANGED_ERP_SLOT;
>>> +
>>
>> I don't know if this is done elsewhere, but this code doesn't match
>> the comment - there is no test for IBSS mode.
>>
>> Thanks,
>>
>
> Do you happen to know any code path that calls
> __ieee80211_sta_join_ibss() without being in IBSS mode ?
Groan.
I clearly need to read patches better.
Thanks,
--
Julian Calaby
Email: julian.calaby@gmail.com
Profile: http://www.google.com/profiles/julian.calaby/
.Plan: http://sites.google.com/site/juliancalaby/
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mac80211: adapt slot time in IBSS mode
2012-12-03 23:00 ` Julian Calaby
2012-12-04 8:08 ` Nicolas Cavallari
@ 2012-12-04 10:42 ` Simon Wunderlich
1 sibling, 0 replies; 6+ messages in thread
From: Simon Wunderlich @ 2012-12-04 10:42 UTC (permalink / raw)
To: Julian Calaby
Cc: Simon Wunderlich, linux-wireless, linville, johannes,
Simon Wunderlich, Mathias Kretschmer
[-- Attachment #1: Type: text/plain, Size: 358 bytes --]
Hey Julian,
On Tue, Dec 04, 2012 at 10:00:33AM +1100, Julian Calaby wrote:
>
> I don't know if this is done elsewhere, but this code doesn't match
> the comment - there is no test for IBSS mode.
As Nicolas pointed out, this is only called in IBSS - it is part of the
ibss join/initialization code, so this is not a problem. :)
Cheers,
Simon
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mac80211: adapt slot time in IBSS mode
2012-12-03 21:21 [PATCH] mac80211: adapt slot time in IBSS mode Simon Wunderlich
2012-12-03 23:00 ` Julian Calaby
@ 2012-12-04 14:54 ` Johannes Berg
1 sibling, 0 replies; 6+ messages in thread
From: Johannes Berg @ 2012-12-04 14:54 UTC (permalink / raw)
To: Simon Wunderlich
Cc: linux-wireless, linville, Simon Wunderlich, Mathias Kretschmer
On Mon, 2012-12-03 at 22:21 +0100, Simon Wunderlich wrote:
> In 5GHz/802.11a, we are allowed to use short slot times. Doing this
> may increases performance by 20% for legacy connections (54 MBit/s).
> I can confirm this in my tests (27% more throughput using iperf), and
> also have a small positive effect (5% more throughput) for HT rates,
> tested on 1 stream.
Applied.
johannes
^ permalink raw reply [flat|nested] 6+ messages in thread
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2012-12-03 21:21 [PATCH] mac80211: adapt slot time in IBSS mode Simon Wunderlich
2012-12-03 23:00 ` Julian Calaby
2012-12-04 8:08 ` Nicolas Cavallari
2012-12-04 22:07 ` Julian Calaby
2012-12-04 10:42 ` Simon Wunderlich
2012-12-04 14:54 ` Johannes Berg
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