On 5/16/2016 4:31 PM, ALeX Wang wrote: > Hi Ferruh, > > Thx for pointing out the 'fill alloc_q with these mubfs _until it gets > full_.', > > I saw the size of all queues are 'KNI_FIFO_COUNT_MAX (1024)'... > The corresponding memory required is more than what I specify as > 'socket_mem' (since i'm using VM)... >
If the mempool is not big enough to fill the ring, this explains the error log. Logic is to fill the alloc_q, but if you are missing the required mbufs, in each rte_kni_rx_burst() it will complain about memory. But the required memory for mbufs to fill the ring is not too much. It should be ~2Mbytes, are you sure you are missing this much memory? > Also, in my use case, I only `tcpreplay` through the kni interface, and > my application only do rx and then free the 'mbufs'. So there is no tx > at all. > > So, in my case, I still think this is a bug/defect, or somewhere i still > misunderstand, > > P.S. The description here seems to be inverted, > http://dpdk.org/doc/api/rte__kni_8h.html#a0cdd727cdc227d005fef22c0189f3dfe > 'rte_kni_rx_burst' does the 'It handles allocating the mbufs for KNI > interface alloc queue.' > You are right. That part of the description for rte_kni_rx_burst and rte_kni_tx_burst needs to be replaced. Do you want to send a patch? > Thanks, > Alex Wang, > > On 16 May 2016 at 04:20, Ferruh Yigit <ferruh.yigit at intel.com > <mailto:ferruh.yigit at intel.com>> wrote: > > On 5/15/2016 5:48 AM, ALeX Wang wrote: > > Hi, > > > > When using the kni module to test my application inside > > debian (virtualbox) VM (kernel version 4.4), I get the > > > > "KNI: Out of memory" > > > > from syslog every time I `tcpreply` packets through > > the kni interface. > > > > After checking source code, I saw that when I call > > 'rte_kni_rx_burst()', no matter how many packets > > are actually retrieved, we always call 'kni_allocate_mbufs()' > > and try allocate 'MAX_MBUF_BURST_NUM' more > > mbufs... I fix the issue via using this patch below, > > > > Could you confirm if this is an actual bug? > > > > Hi Alex, > > I don't think this is a bug. > > kni_allocate_mbufs() will allocate MAX_MBUF_BURST_NUM mbufs as you > mentioned. And will fill alloc_q with these mubfs _until it gets full_. > And if the alloc_q is full and there are remaining mbufs, they will be > freed. So for some cases this isn't the most optimized way, but there is > no defect. > > Since you are getting "KNI: Out of memory", somewhere else can be > missing freeing mbufs. > > mbufs freeing done in rte_kni_tx_burst(), I can guess two cases that can > cause problem: > a) not calling rte_kni_tx_burst() frequent, so that all free mbufs > consumed. > b) calling rte_kni_tx_burst() with number of mbufs bigger than > MAX_MBUF_BURST_NUM, because this function frees at most > MAX_MBUF_BURST_NUM of mbufs, but if you are calling calling > rte_kni_tx_burst() with bigger numbers, this will cause mbufs to stuck > in free_q > > > Regards, > ferruh > > > > > > -- > Alex Wang, > Open vSwitch developer
