Re: ipc,sem: sysv semaphore scalability

From: Emmanuel Benisty
Date: Fri Mar 29 2013 - 23:02:35 EST


Hi Davidlohr,

On Sat, Mar 30, 2013 at 9:08 AM, Davidlohr Bueso <davidlohr.bueso@xxxxxx> wrote:
> Not sure which one liner you refer to, but, if you haven't already done
> so, please try with these fixes (queued in linux-next):
>
> http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=a9cead0347283f3e72a39e7b76a3cc479b048e51
> http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=4db64b89525ac357cba754c3120065adddd9ec31
>
> I've been trying to reproduce your twilight zone problem on five
> different machines now without any luck. Is there anything you're doing
> to trigger the issue? Does the machine boot ok and then do weird things,
> say after X starts, open some program, etc?

I was missing a9cead0, thanks. What I usually do is starting a
standard session, which looks like this:

init-+-5*[agetty]
|-bash---startx---xinit-+-X---2*[{X}]
| `-dwm---sh---sleep
|-bash---chromium-+-chromium
| |-chromium-+-chromium
| | `-2*[{chromium}]
|
|-chromium-sandbo---chromium---chromium---4*[chromium---4*[{chromium}]]
| `-65*[{chromium}]
|-crond
|-dbus-daemon
|-klogd
|-syslogd
|-tmux-+-alsamixer
| |-bash---bash
| |-bash
| |-htop
| `-newsbeuter---{newsbeuter}
|-udevd
|-urxvtd-+-bash---pstree
| `-bash---tmux
`-wpa_supplicant

Then I start building a random package and the problems start. They
may also happen without compiling but this seems to trigger the bug
quite quickly. Anyway, some progress here, I hope: dmesg seems to be
willing to reveal some secrets (using some pastebin service since this
is pretty big):

https://gist.github.com/anonymous/5275120

Thanks.
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