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    SubjectRe: stmmac ethernet in kernel 4.4: coalescing related pauses?
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    On 28.11.2016 16:31, Eric Dumazet wrote:
    > On Mon, 2016-11-28 at 09:54 -0500, David Miller wrote:
    >> From: Lino Sanfilippo <lsanfil@marvell.com>
    >> Date: Mon, 28 Nov 2016 14:07:51 +0100
    >>
    >>> Calling skb_orphan() in the xmit handler made this issue disappear.
    >>
    >> This is not the way to handle this problem.
    >>
    >> The solution is to free the SKBs in a timely manner after the
    >> chip has transmitted the frame.
    >
    > Note that the 'pauses' described by Pavel are also caused by a too small
    > SO_SNDBUF value on the UDP socket.
    >
    > An immediate fix, with no kernel change is to increase it.
    >
    > echo 1000000 >/proc/sys/net/core/wmem_default
    >
    > or
    >
    > val = 1000000;
    > setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &val, sizeof(val));
    >

    I wonder if the best fix would be indeed to deactivate irq coalescing completely.
    Does it make any sense at all to use it if a driver uses NAPI already?

    Regards,
    Lino

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