On Wed, Sep 17, 2014 at 03:52:52AM -0700, Amitkumar Karwar 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. If you get time, I'd also appreciate a look into the issue on sdio.c during data receive. When dev_alloc_skb fails the interrupt handler does not rewind the driver state in preparation for a retry. This is not graceful. http://dev.laptop.org/ticket/12694 has details, and an adequate solution we are using in 3.5 to rewind the driver state: http://dev.laptop.org/git/olpc-kernel/commit/?h=arm-3.5&id=59fcaf10cce5bbdc370ec1c262b12aeb66ed1dca We're using 8787. > > > 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 > N?????r??y????b?X??ǧv?^?){.n?+????{??*ޕ?,?{ay? ʇڙ?,j??f???h???z? ?w??? ???j:+v???w?j?m????????zZ+?????ݢj"??! -- James Cameron http://quozl.linux.org.au/ -- 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
