[dpdk-dev] Questions about TX descriptors run out occasionally

[刘辉 <h.liu@alibaba-inc.com>]

Hi Experts,

I'm developing my own dpdk-based application via Intel 82599ES port. My Application is doing a job to send ICMP requests (packet size varies from 64 bytes to 1472 bytes, 200,000 pps, 1.1Gbps) and receive responses, with ARP request/response and ICMP response handling when necessary. It was working pretty fine in 5 hours to 10 days  randomly and then TX descriptors run out and cannot be freed by ixgbe_tx_free_bufs() due to DD bit is not set:

        /* check DD bit on threshold descriptor */
        status = txq->tx_ring[txq->tx_next_dd].wb.status;
        if (!(status & IXGBE_ADVTXD_STAT_DD))
                return 0;

My tx queue setup is:
        tx_conf->tx_thresh.pthresh = 64;
        tx_conf->tx_thresh.hthresh = 0;
        tx_conf->tx_thresh.wthresh = 0;
        tx_conf->tx_free_thresh = 256;
        tx_conf->tx_rs_thresh = 32;
        tx_conf->txq_flags = ETH_TXQ_FLAGS_NOMULTSEGS | ETH_TXQ_FLAGS_NOOFFLOADS;


I tried to read code to see if there is any case to take these descriptors and never set IXGBE_ADVTXD_STAT_DD back but no luck yet. And I have not even found the related code when IXGBE_ADVTXD_STAT_DD is set/unset when descriptor is taken/released other than reset queues... So may I ask:
1. where do we set/unset IXGBE_ADVTXD_STAT_DD when descriptor is taken/released?
2. any suggestion or information I should focus on to debug this issue? Is this typically because of my upper application not alloc/free correctly or any other problem?
3. another friend in dpdk-user list raised same issue in fm10k driver, but later he mentioned his problem was because of overheating of NIC (temperature was close to 85 degree Celsius). After setting system FAN to full speed, he made it work perfectly. Since in my system I don't have fan/temp sensors so I could not check this. Might this problem be caused by high temperature in case?

Regards,
Hui 

from Alimail macOS