From: Eric Dumazet <edumazet@google.com>
Date: Mon, 5 Nov 2012 16:20:42 +0000 (+0000)
Subject: mlx4: change TX coalescing defaults
X-Git-Tag: omap-for-v3.8/fixes-for-merge-window-v4-signed~45^2~424
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ecfd2ce1a9d5e6376ff5c00b366345160abdbbb7;p=pandora-kernel.git

mlx4: change TX coalescing defaults

mlx4 currently uses a too high tx coalescing setting, deferring
TX completion interrupts by up to 128 us.

With the recent skb_orphan() removal in commit 8112ec3b872,
performance of a single TCP flow is capped to ~4 Gbps, unless
we increase tcp_limit_output_bytes.

I suggest using 16 us instead of 128 us, allowing a finer control.

Performance of a single TCP flow is restored to previous levels,
while keeping TCP small queues fully enabled with default sysctl.

This patch is also a BQL prereq.

Reported-by: Vimalkumar <j.vimal@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yevgeny Petrilin <yevgenyp@mellanox.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Acked-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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