From: David Miller <davem@davemloft.net>
To: simon.guinot@sequanux.org
Cc: thomas.petazzoni@free-electrons.com, netdev@vger.kernel.org,
musv@gmx.de, andreas.tobler@cloudguard.ch,
gregory.clement@free-electrons.com,
antoine.tenart@free-electrons.com, mw@semihalf.com,
stable@vger.kernel.org
Subject: Re: [PATCH] net: mvneta: fix handling of the Tx descriptor counter
Date: Sat, 11 Nov 2017 18:45:04 +0900 (KST) [thread overview]
Message-ID: <20171111.184504.2151388779461931723.davem@davemloft.net> (raw)
In-Reply-To: <20171108165835.13453-1-simon.guinot@sequanux.org>
From: Simon Guinot <simon.guinot@sequanux.org>
Date: Wed, 8 Nov 2017 17:58:35 +0100
> @@ -2413,8 +2416,7 @@ static int mvneta_tx(struct sk_buff *skb, struct net_device *dev)
> if (txq->count >= txq->tx_stop_threshold)
> netif_tx_stop_queue(nq);
>
> - if (!skb->xmit_more || netif_xmit_stopped(nq) ||
> - txq->pending + frags > MVNETA_TXQ_DEC_SENT_MASK)
> + if (!skb->xmit_more || netif_xmit_stopped(nq))
> mvneta_txq_pend_desc_add(pp, txq, frags);
> else
> txq->pending += frags;
As David Laight said, you should not allow unlimited amounts of
->xmit_more frames to be queued without a TX doorbell update.
Therefore, please keep some kind of limit here otherwise latency
will spike in some circumstances.
next prev parent reply other threads:[~2017-11-11 9:45 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20171018223425.42ce7a74@gmx.de>
2017-10-18 20:55 ` Problems with mvneta Thomas Petazzoni
2017-10-19 22:25 ` Sven Müller
2017-10-20 7:09 ` Thomas Petazzoni
2017-10-23 6:29 ` Andreas Tobler
2017-10-23 9:30 ` Sven Müller
2017-10-31 14:23 ` Sven Müller
2017-10-31 14:27 ` Thomas Petazzoni
2017-10-31 17:09 ` Simon Guinot
2017-10-31 20:23 ` Thomas Petazzoni
2017-11-01 8:10 ` Marcin Wojtas
2017-11-08 16:58 ` [PATCH] net: mvneta: fix handling of the Tx descriptor counter Simon Guinot
2017-11-08 17:03 ` David Laight
2017-11-08 17:17 ` Simon Guinot
2017-11-09 19:19 ` Andreas Tobler
2017-11-11 9:45 ` David Miller [this message]
2017-11-13 14:51 ` Simon Guinot
2017-11-13 14:54 ` David Miller
2017-11-13 15:36 ` Simon Guinot
2017-11-20 14:58 ` David Laight
2017-11-13 15:27 ` [PATCH v2] " Simon Guinot
2017-11-14 12:53 ` David Miller
2017-11-10 10:22 ` [PATCH] " Sven Müller
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