From: "Qing Wan" <qwan@evertz.com>
To: <dev@dpdk.org>
Subject: [dpdk-dev] condition for calling ixgbe_xmit_cleanup
Date: Wed, 12 Feb 2014 17:50:03 -0500 [thread overview]
Message-ID: <C70A636B101FD44999B82525C3E92AFA0348FDAF@otis.burlington.evertz.tv> (raw)
Hi,
There are following code in function ixgbe_xmit_pkts,
....
if ((txq->nb_tx_desc - txq->nb_tx_free) > txq->tx_free_thresh) {
ixgbe_xmit_cleanup(txq);
}
....
My understanding is, nb_tx_desc means total number of descriptors in
ring and nx_tx_free represents how many descriptors are available, so
txq->nb_tx_desc - txq->nb_tx_free means how many we have used. I'm not
quite understand the meaning of this comparison. Why is the condition
not something like "if (txq->nb_tx_free < tx_free_thresh)".
really appreciate if someone could help me on this.
Thanks
Qing
next reply other threads:[~2014-02-12 22:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-12 22:50 Qing Wan [this message]
2014-02-12 23:31 ` Shaw, Jeffrey B
2014-02-13 14:59 ` Qing Wan
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