Thread: [Madwifi-devel] Channel changing time
Status: Beta
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From: Jong H. Z. <mai...@gm...> - 2004-09-30 10:51:27
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I know that switching between channels in madwifi involve full reset operation, and in one of the previous posts, http://sourceforge.net/mailarchive/message.php?msg_id=6324179 Sam mentioned that "What goes on at reset is very chip specific and explaining it basically requires you to know how the hardware works. The main tasks are to setup the DMA engine(s) and program the radio." So, it seems to me like ath_hal_reset is a time consuming operation. I'm looking for a way to change channel quickly, so I'm wondering whether this can be done without full reset? -- Jong Hian Zin |
From: Sam L. <sa...@er...> - 2004-09-30 16:19:21
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Jong Hian Zin wrote: > I know that switching between channels in madwifi involve full reset > operation, and in one of the previous posts, > > http://sourceforge.net/mailarchive/message.php?msg_id=6324179 > > Sam mentioned that "What goes on at reset is very chip specific and > explaining it basically requires you to know how the hardware works. > The main tasks are to setup the DMA engine(s) and program the radio." I said this for a completely unrelated question. > So, it seems to me like ath_hal_reset is a time consuming operation. Not sure how you arrived at this. > > I'm looking for a way to change channel quickly, so I'm wondering > whether this can be done without full reset? > A channel change requires a call to ath_hal_reset. The original poster was measuring channel change time using an ioctl; this potentially includes many other tasks unrelated to changing the channel. If you want to measure how long it takes to change the channel, instrument the time required to carry out an ath_hal_reset call. Sam |
From: Jean L. <lo...@cl...> - 2004-10-01 07:05:24
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Hi everyone ! Last time I checked, channel reset took from <10 to 40 ms. This includes the time for ath_hal_reset among others. It's the time measured between the last frame on the previous channel and the first frame on the next channel. It is however very changing, and depends on the machine load. In addition, I did the measurements with a 10ms resolution so zero delays mean < 10ms... Hope this helps Jean Jong Hian Zin wrote: > What other operations that ath_hal_reset actually perform beside > setting channel? Any reason that you don't implement a specific > function in HAL just for changing channel? > > On Thu, 30 Sep 2004 09:18:34 -0700, Sam Leffler <sa...@er...> wrote: > >>Jong Hian Zin wrote: >> >>>I know that switching between channels in madwifi involve full reset >>>operation, and in one of the previous posts, >>> >>>http://sourceforge.net/mailarchive/message.php?msg_id=6324179 >>> >>>Sam mentioned that "What goes on at reset is very chip specific and >>>explaining it basically requires you to know how the hardware works. >>>The main tasks are to setup the DMA engine(s) and program the radio." >> >>I said this for a completely unrelated question. >> >> >>>So, it seems to me like ath_hal_reset is a time consuming operation. >> >>Not sure how you arrived at this. >> >> >>>I'm looking for a way to change channel quickly, so I'm wondering >>>whether this can be done without full reset? >>> >> >>A channel change requires a call to ath_hal_reset. The original poster >>was measuring channel change time using an ioctl; this potentially >>includes many other tasks unrelated to changing the channel. If you >>want to measure how long it takes to change the channel, instrument the >>time required to carry out an ath_hal_reset call. >> >> Sam >> > > |
From: Steffen P. <st...@wh...> - 2004-10-01 15:05:54
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Hi, I got down to a minimum of ~3 ms of changing time by playing with the ieee80211 statemachine. I did only one scan and cycled trough the availible APs in the scan list ;) I think thats the minimum because you'll need some time to exchange all the management frames! Greeting, Steffen -- Steffen Pfendtner <st...@wh...> GPG Key fingerprint = DF91 11BB 498F 573B 8002 6E0B 3AE3 FF88 EADD B3BC |
From: Jong H. Z. <mai...@gm...> - 2004-09-30 22:32:17
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What other operations that ath_hal_reset actually perform beside setting channel? Any reason that you don't implement a specific function in HAL just for changing channel? On Thu, 30 Sep 2004 09:18:34 -0700, Sam Leffler <sa...@er...> wrote: > Jong Hian Zin wrote: > > I know that switching between channels in madwifi involve full reset > > operation, and in one of the previous posts, > > > > http://sourceforge.net/mailarchive/message.php?msg_id=6324179 > > > > Sam mentioned that "What goes on at reset is very chip specific and > > explaining it basically requires you to know how the hardware works. > > The main tasks are to setup the DMA engine(s) and program the radio." > > I said this for a completely unrelated question. > > > So, it seems to me like ath_hal_reset is a time consuming operation. > > Not sure how you arrived at this. > > > > > I'm looking for a way to change channel quickly, so I'm wondering > > whether this can be done without full reset? > > > > A channel change requires a call to ath_hal_reset. The original poster > was measuring channel change time using an ioctl; this potentially > includes many other tasks unrelated to changing the channel. If you > want to measure how long it takes to change the channel, instrument the > time required to carry out an ath_hal_reset call. > > Sam > -- Jong Hian Zin |
From: Jong H. Z. <mai...@gm...> - 2004-10-02 05:29:25
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FYI, I have measured the time for carrying out a ath_hal_reset call, which is about 1.46 ms on my AR5212 802.11b/g CardBus adapter. This is very fast indeed, I should have measured it before posting the previous questions. On Fri, 1 Oct 2004 06:32:15 +0800, Jong Hian Zin <mai...@gm...> wrote: > What other operations that ath_hal_reset actually perform beside > setting channel? Any reason that you don't implement a specific > function in HAL just for changing channel? > > > > On Thu, 30 Sep 2004 09:18:34 -0700, Sam Leffler <sa...@er...> wrote: > > Jong Hian Zin wrote: > > > I know that switching between channels in madwifi involve full reset > > > operation, and in one of the previous posts, > > > > > > http://sourceforge.net/mailarchive/message.php?msg_id=6324179 > > > > > > Sam mentioned that "What goes on at reset is very chip specific and > > > explaining it basically requires you to know how the hardware works. > > > The main tasks are to setup the DMA engine(s) and program the radio." > > > > I said this for a completely unrelated question. > > > > > So, it seems to me like ath_hal_reset is a time consuming operation. > > > > Not sure how you arrived at this. > > > > > > > > I'm looking for a way to change channel quickly, so I'm wondering > > > whether this can be done without full reset? > > > > > > > A channel change requires a call to ath_hal_reset. The original poster > > was measuring channel change time using an ioctl; this potentially > > includes many other tasks unrelated to changing the channel. If you > > want to measure how long it takes to change the channel, instrument the > > time required to carry out an ath_hal_reset call. > > > > Sam > > > > -- > Jong Hian Zin > -- Jong Hian Zin |