From: Amir Vadai <amirv.mellanox@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>, Amir Vadai <amirv@mellanox.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
netdev@vger.kernel.org, Yevgeny Petrilin <yevgenyp@mellanox.com>,
Or Gerlitz <ogerlitz@mellanox.com>,
Ido Shamay <idos@mellanox.com>
Subject: Re: [PATCH net-next] net/mlx4_en: remove NETDEV_TX_BUSY
Date: Tue, 07 Oct 2014 11:30:06 +0300 [thread overview]
Message-ID: <5433A48E.1040505@gmail.com> (raw)
In-Reply-To: <1412613035.11091.72.camel@edumazet-glaptop2.roam.corp.google.com>
On 10/6/2014 7:30 PM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> Drivers should avoid NETDEV_TX_BUSY as much as possible.
>
> They should stop the tx queue before qdisc even tries to push another
> packet, to avoid requeues.
>
> For a driver supporting skb->xmit_more, this is likely to be a prereq
> anyway, otherwise we could have a tx deadlock : We need to force a
> doorbell if TX ring is full.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---
Reviewed. Also verified that it fixes the deadlock (by sending a large
burst - larger than ring size). Before this fix, last packet of the
burst wasn't sent, therefore no doorbell was rang, and the queue was
stalled.
BTW, another nice optimization that we hope to send soon, is not to arm
the CQ unless ringing the doorbell.
Acked-by: Amir Vadai <amirv@mellanox.com>
next prev parent reply other threads:[~2014-10-07 8:30 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-06 6:15 [PATCH net-next V1 00/14] net/mlx4_en: Optimizations to TX flow Amir Vadai
2014-10-06 6:15 ` [PATCH net-next V1 01/14] net/mlx4_en: Code cleanups in tx path Amir Vadai
2014-10-06 6:15 ` [PATCH net-next V1 02/14] net/mlx4_en: Align tx path structures to cache lines Amir Vadai
2014-10-06 6:15 ` [PATCH net-next V1 03/14] net/mlx4_en: Avoid calling bswap in tx fast path Amir Vadai
2014-10-06 6:15 ` [PATCH net-next V1 04/14] net/mlx4_en: tx_info allocated with kmalloc() instead of vmalloc() Amir Vadai
2014-10-06 6:15 ` [PATCH net-next V1 05/14] net/mlx4_en: Avoid a cache line miss in TX completion for single frag skb's Amir Vadai
2014-10-06 6:15 ` [PATCH net-next V1 06/14] net/mlx4_en: Use prefetch in tx path Amir Vadai
2014-10-06 6:15 ` [PATCH net-next V1 07/14] net/mlx4_en: Avoid false sharing in mlx4_en_en_process_tx_cq() Amir Vadai
2014-10-06 6:15 ` [PATCH net-next V1 08/14] net/mlx4_en: mlx4_en_xmit() reads ring->cons once, and ahead of time to avoid stalls Amir Vadai
2014-10-06 6:15 ` [PATCH net-next V1 09/14] net/mlx4_en: Use local var in tx flow for skb_shinfo(skb) Amir Vadai
2014-10-06 6:15 ` [PATCH net-next V1 10/14] net/mlx4_en: Use local var for skb_headlen(skb) Amir Vadai
2014-10-06 6:16 ` [PATCH net-next V1 11/14] net/mlx4_en: tx_info->ts_requested was not cleared Amir Vadai
2014-10-06 6:16 ` [PATCH net-next V1 12/14] net/mlx4_en: Enable the compiler to make is_inline() inlined Amir Vadai
2014-10-06 6:16 ` [PATCH net-next V1 13/14] ethtool: Ethtool parameter to dynamically change tx_copybreak Amir Vadai
2014-10-06 6:16 ` [PATCH net-next V1 14/14] net/mlx4_en: Use the new tx_copybreak to set inline threshold Amir Vadai
2014-10-06 12:51 ` [PATCH net-next V1 00/14] net/mlx4_en: Optimizations to TX flow Eric Dumazet
2014-10-06 12:54 ` Amir Vadai
2014-10-06 16:30 ` [PATCH net-next] net/mlx4_en: remove NETDEV_TX_BUSY Eric Dumazet
2014-10-07 8:30 ` Amir Vadai [this message]
2014-10-07 12:38 ` Eric Dumazet
2014-10-07 17:21 ` David Miller
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