On 17 May 2016 at 03:07, Ferruh Yigit <ferruh.yigit at intel.com> wrote:
> 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? > > Thx for reminding me about this, by default, i only allocate 2048 mbufs for my pool... once i raise it to 4096, the issue is gone... will the `KNI_FIFO_COUNT_MAX ` ever change? I want to try adding some documentation,... > > 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? > > Sure, will do that, Thanks, Alex Wang, > > 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 > > -- Alex Wang, Open vSwitch developer
