Re: [Madwifi-users] Ksoftirqd/0 eating all my CPU while transfer

[Jiri F. <jir...@hl...>]

Hello

I had related problem with 0.9.4. It was caused by wrong txqueue handling:

http://madwifi-project.org/browser/madwifi/branches/madwifi-0.9.4/ath/if_ath.c

> 7473 	                if (sc->sc_devstopped) {
> 7474 	                        ++sc->sc_reapcount;
> 7475 	                        if (sc->sc_reapcount > ATH_TXBUF_FREE_THRESHOLD) {
> 7476 	                                if (!sc->sc_dfswait)
> 7477 	                                        netif_start_queue(sc->sc_dev);
> 7478 	                                DPRINTF(sc, ATH_DEBUG_TX_PROC,
> 7479 	                                        "%s: tx tasklet restart the queue\n",
> 7480 	                                        __func__);
> 7481 	                                sc->sc_reapcount = 0;
> 7482 	                                sc->sc_devstopped = 0;
> 7483 	                        } else
> 7484 	                                ATH_SCHEDULE_TQUEUE(&sc->sc_txtq, NULL);
> 7485 	                }

In some condition TX queue tasklet at line 7483/7484 trying reshedule 
itself forever whish causing high cpu load. Quick and dirty hack should 
be completly remove else condition to reschedule the tasklet, but over 
the code are a lot more coding issues regarding TX queue handling. I 
have done patch fixing all those issues but it may not be compatible 
with official 0.9.4 branch:
http://hyperfighter.sk/madwifi-0.9.4-free-jf/176-queue_handling_fix.patch

Jiri


On 12/15/2009 08:13 PM, Gleidson Antônio Henriques wrote:
> After some tests I've noted that all madwifi versions 0.9.4 are CPU
> intensive while in AP mode.
> I did some tests with madwifi 0.9.3 and the problem stopped.
> Is there a way to implement minstrel rate in 0.9.3 driver ?
> Thanks in advance,
> Gleidson
>
>     ----- Original Message -----
>     *From:* Gleidson Antônio Henriques <mailto:gle...@pr...>
>     *To:* Brett Wright <mailto:Bre...@el...> ;
>     mad...@li...
>     <mailto:mad...@li...>
>     *Sent:* Tuesday, December 15, 2009 3:09 PM
>     *Subject:* Re: [Madwifi-users] Ksoftirqd/0 eating all my CPU while
>     transfer
>
>     Thanks for your response Brett,
>     I tried disable Interference Mitigation but the problem still occurs.
>     Thanks in advance,
>     Gleidson
>
>         ----- Original Message -----
>         *From:* Brett Wright <mailto:Bre...@el...>
>         *To:* Gleidson Antônio Henriques
>         <mailto:gle...@pr...> ;
>         mad...@li...
>         <mailto:mad...@li...>
>         *Sent:* Tuesday, December 15, 2009 12:23 AM
>         *Subject:* RE: [Madwifi-users] Ksoftirqd/0 eating all my CPU
>         while transfer
>
>         Hi,
>
>         I have seen similar things on an AP when interference mitigation
>         is turned on.
>
>         You can try turning this off using something like:
>
>         echo 0 > /proc/sys/net/dev/wifi0/intmit
>
>         (your proc file location might be slightly different). This
>         should free up your CPU but your throughput may suffer depending
>         on the level of interference.
>
>         Brett
>
>         ------------------------------------------------------------------------
>
>         *From:* Gleidson Antônio Henriques
>         [mailto:gle...@pr...]
>         *Sent:* Tuesday, 15 December 2009 10:18 AM
>         *To:* mad...@li...
>         *Subject:* [Madwifi-users] Ksoftirqd/0 eating all my CPU while
>         transfer
>
>         Hi all,
>
>         I'd encountered a problem with different versions of Madwifi +
>         different versions of kernels and I'm totally lost.
>
>         My scenario is: 2 - Alix.2D2 ( One configured as AP and another
>         configured as Station )
>
>         2 - Wireless Card ( Model: CM9-GP )
>
>         Madwifi driver version 0.9.4 ( but already tested with latest
>         trunk version )
>
>         Kernel 2.6.21 ( but already tested against other versions of
>         kernel )
>
>         If i grab one file from AP using the Station, ksoftirqd at AP
>         starts to eat all my CPU until the transfer stops.
>
>         I achieve 3,1 MB/s throughtput rate but I lost my entire CPU.
>
>         I don't know how it could be possible but if I install
>         voyage-linux distro 0.6.2 ( with madwifi driver version
>         0.9.4+r4022.20090513-1+6.0-3 ), I can
>
>         achieve the same throughput without the stress on CPU.
>
>         Is there anyone that encountered this kind of problem ?
>
>         Thanks in advance,
>
>         Gleidson Antonio Henriques
>
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