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From: Jason Baron <jbaron@akamai.com>
To: Eric Dumazet <eric.dumazet@gmail.com>,
	David Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Subject: Re: [PATCH v2 net-next] tcp: set SOCK_NOSPACE under memory pressure
Date: Fri, 15 May 2015 10:20:38 -0400	[thread overview]
Message-ID: <555600B6.4040400@akamai.com> (raw)
In-Reply-To: <1431659228.27831.89.camel@edumazet-glaptop2.roam.corp.google.com>

On 05/14/2015 11:07 PM, Eric Dumazet wrote:
> On Sat, 2015-05-09 at 17:38 -0400, David Miller wrote:
>> Applied, thanks a lot for adding so much information to the commit
>> message.
>> --
> When doing more tests with this stuff, I found we could still have
> hangs, because a TCP socket can end up having no skb in its write queue.
>
> We need to allow one skb (this can be 2KB) to keep the logic being ACK
> driven.
>

Indeed. I alluded to that in the commit message.

The 2KB minimum wouldn't help in the case where we really got
-ENOMEM from the core allocator, unless I guess we reserved
the 2KB permanently. Or we could just issue the wakeup in the
case where we return -EAGAIN and the write queue is empty.
That is a very simple additional change here, I think.

Thanks,

-Jason

  reply	other threads:[~2015-05-15 14:20 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-06 15:52 [PATCH v2 net-next] tcp: set SOCK_NOSPACE under memory pressure Jason Baron
2015-05-06 16:13 ` Eric Dumazet
2015-05-09 21:38 ` David Miller
2015-05-15  3:07   ` Eric Dumazet
2015-05-15 14:20     ` Jason Baron [this message]
2015-05-15 14:50       ` Eric Dumazet

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