[-next regression] TCP window full with EPOLLWAKEUP [LWN.net]

From:		Jiri Slaby <jslaby-AT-suse.cz>
To:		Arve Hjønnevåg <arve-AT-android.com>
Subject:		[-next regression] TCP window full with EPOLLWAKEUP
Date:		Sun, 20 May 2012 00:06:57 +0200
Message-ID:		<4FB81981.3050509@suse.cz>
Cc:		NeilBrown <neilb-AT-suse.de>, "Rafael J. Wysocki" <rjw-AT-sisk.pl>, LKML <linux-kernel-AT-vger.kernel.org>, Jiri Slaby <jirislaby-AT-gmail.com>
Archive-link:		Article, Thread

Hi,

a bisection shows that with the following commit from -next:
commit 4d7e30d98939a0340022ccd49325a3d70f7e0238
Author: Arve Hjønnevåg <arve@android.com>
Date:   Tue May 1 21:33:34 2012 +0200

    epoll: Add a flag, EPOLLWAKEUP, to prevent suspend while epoll
events are ready

====

one of mono programs I use stops receiving data from the network.
Wireshark shows that the TCP window of a connection is filled. This
means the program does not read the data fast enough after requesting
the data.

If I revert that commit on the top of -next (20120518), everything works
as expected.

regards,
-- 
js
suse labs

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