Re: Enabling linux kernel jit compiler from dumpcap?

[Bálint Réczey <balint () balintreczey hu>]

2013/8/23 Anders Broman <anders.broman () ericsson com>:
> > before we change it, should we remember the previous setting and restore it when dumpcap exits?
>
> Preferably yes but I'm not sure it's possible as I think root privileges are required to write to the file and I 
> think dumpcap
> Drops those after starting to capture.
And in the configuration the documentation recommends dumpcap does not
run as root, it has permission to capture only.

Cheers,
Balint

> Regards
> Anders
>
> -----Original Message-----
> From: wireshark-dev-bounces () wireshark org [mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Martin 
> Kaiser
> Sent: den 23 augusti 2013 10:36
> To: wireshark-dev () wireshark org
> Subject: Re: [Wireshark-dev] Enabling linux kernel jit compiler from dumpcap?
>
> before we change it, should we remember the previous setting and restore it when dumpcap exits?
>
> Thus wrote Anders Broman (a.broman () bredband net):
>
> > Bálint Réczey skrev 2013-08-22 23:02:
> > > Hi,
>
> > > I would be happier if the applications I run did not change kernel
> > > configuration without my consent.
> > I see your point...
>
> > > Regarding Wireshark I would prefer suggesting "echo 1 >
> > > /proc/sys/net/core/bpf_jit_enable" in the documentation instead of
> > > adding code to enable JIT.
> > > There may be good reasons for not enabling it by default in the Linux kernel.
> > The problematic thing is that people seldom reads the documentation,
> > the setting gets reset at a reboot and it's easy to forget to
> > re-enable it. The ideal thing would be if dumpcap
> > - Had a preference/command line flag whether to use JIT or not.
> > - If told to use it check if it was enabled or not used JIT and put it
> > back to zero if not set when starting.
> > Wireshark could then default to use JIT and some warnings could be
> > displayed in the welcome screen and in dumpcaps help output.
>
> > netsniff-ng activates it by default it seems.
> > Regards
> > Anders
>
> > > Cheers,
> > > Balint
>
> > > 2013/8/22 Anders Broman <a.broman () bredband net>:
> > > > Guy Harris skrev 2013-08-22 18:16:
>
> > > > > On Aug 22, 2013, at 4:46 AM, Anders Broman
> > > > > <anders.broman () ericsson com>
> > > > > wrote:
>
> > > > > > Should we add code to enable the JIT compiler from dumpcap?
> > > > > Should I add code to enable the JIT compiler to libpcap while I'm at it?
>
> > > > > Should the Linux kernel folks enable it by default?
>
> > > > > I'm inclined to answer "yes" to all three questions.  I think the
> > > > > FreeBSD JIT compiler is enabled by default.  I'm surprised that the Linux one isn't.
> > > > I checked in the dumpcap code. I agree that it might be useful in
> > > > libpcap too, root privileges are required to change it I think. and
> > > > Yes
>
> > > > > I'm surprised that the Linux one isn't
> > > > Regards
> > > > Anders
>
> > > > > ___________________________________________________________________________
> > > > > Sent via:    Wireshark-dev mailing list <wireshark-dev () wireshark org>
> > > > > Archives:    http://www.wireshark.org/lists/wireshark-dev
> > > > > Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev
>
> > > > > mailto:wireshark-dev-request () wireshark org?subject=unsubscribe
>
> > > > ___________________________________________________________________________
> > > > Sent via:    Wireshark-dev mailing list <wireshark-dev () wireshark org>
> > > > Archives:    http://www.wireshark.org/lists/wireshark-dev
> > > > Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev
> > > >
> > > > mailto:wireshark-dev-request () wireshark org?subject=unsubscribe
> > > ___________________________________________________________________________
> > > Sent via:    Wireshark-dev mailing list <wireshark-dev () wireshark org>
> > > Archives:    http://www.wireshark.org/lists/wireshark-dev
> > > Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev
> > >
> > > mailto:wireshark-dev-request () wireshark org?subject=unsubscribe
>
>
> > ___________________________________________________________________________
> > Sent via:    Wireshark-dev mailing list <wireshark-dev () wireshark org>
> > Archives:    http://www.wireshark.org/lists/wireshark-dev
> > Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev
> >
> > mailto:wireshark-dev-request () wireshark org?subject=unsubscribe
> ___________________________________________________________________________
> Sent via:    Wireshark-dev mailing list <wireshark-dev () wireshark org>
> Archives:    http://www.wireshark.org/lists/wireshark-dev
> Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev
>              mailto:wireshark-dev-request () wireshark org?subject=unsubscribe
> ___________________________________________________________________________
> Sent via:    Wireshark-dev mailing list <wireshark-dev () wireshark org>
> Archives:    http://www.wireshark.org/lists/wireshark-dev
> Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev
>              mailto:wireshark-dev-request () wireshark org?subject=unsubscribe
___________________________________________________________________________
Sent via:    Wireshark-dev mailing list <wireshark-dev () wireshark org>
Archives:    http://www.wireshark.org/lists/wireshark-dev
Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev
             mailto:wireshark-dev-request () wireshark org?subject=unsubscribe