Dear Amitkumar Karwar, On Wed, Sep 17, 2014 at 12:52 PM, Amitkumar Karwar <akarwar@xxxxxxxxxxx> wrote: > Hi BR, > >> Dear Amitkumar Karwar, >> >> some additional info. >> >> On Thu, Sep 11, 2014 at 5:09 PM, Amitkumar Karwar <akarwar@xxxxxxxxxxx> >> wrote: >> > Hi BR, >> > >> >> >> >> I'm using 3.9 mainline mwifiex driver for wireless usb card. Doing >> >> some throughput testing (with iperf) in 5GHz I got following >> failures: >> >> [ 221.521799] usb 1-1: mwifiex_usb_submit_rx_urb: dev_alloc_skb >> >> failed >> > >> > This is skb allocation failure returned by kernel. 4k buffer is >> always allocated for Rx packets. This issue doesn't seem to be specific >> to 5Ghz. >> Yes you're right. I can reproduce issue also with 2.4GHz (doing iperf >> testing as mentioned in other email) by pinging device with card. >> > >> >> >> >> I checked which which size fails to allocate and it's 4096 bytes. I >> >> was looking to changes in never kernel releases but I cannot find >> >> anything obvious. When connected to 2.4GHz I cannot reproduce issue >> >> though. I'm using FW version mwifiex 1.0 (14.68.29.p26). >> >> >> > >> > Could you please provide the platform details? >> > How often the problem occurs during throughput testing? Are there any >> specific steps? >> One more observation is that when problem occurred complete system is >> unresponsive (console is almost completely dead). > > Thanks for the more information. > Skb alloc failure should be gracefully handled. We will look into this issue. I did small investigation (will my limited networking knowledge :)) and to avoid usb issue I did small hack to free received packet in skb (with specific size 1574 which sends iperf) before sending for processing to driver workqueue. With this small hack I can run iperf -b100m on client size without any allocation issue. Bit more testing shows that 11n rx reordering is in place when receiving packets send from iperf. Is there any know issue in this area which could lead to issues described in my report? BTW I tested backports driver from 3.17-rc3 and issue is still present. > >> I can workaround issue by decreasing iperf bandwidth to ~40m. I think >> in this situation we're running out of memory by exhaustive skb >> allocations. > > Actually 6 4K size buffers are being allocated for Rx and Tx data during traffic. > Probably your platform runs out of memory after these allocations. > > Could you please try changing this number(MWIFIEX_TX_DATA_URB/MWIFIEX_RX_DATA_URB macros) to 3? > > Regards, > Amitkumar Karwar BR, marek -- as simple and primitive as possible ------------------------------------------------- Marek Belisko - OPEN-NANDRA Freelance Developer Ruska Nova Ves 219 | Presov, 08005 Slovak Republic Tel: +421 915 052 184 skype: marekwhite twitter: #opennandra web: http://open-nandra.com -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
