Home page logo
/

wireshark logo Wireshark mailing list archives

Re: Enabling linux kernel jit compiler from dumpcap?
From: Martin Kaiser <lists () kaiser cx>
Date: Fri, 23 Aug 2013 10:36:09 +0200

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


  By Date           By Thread  

Current thread:
[ Nmap | Sec Tools | Mailing Lists | Site News | About/Contact | Advertising | Privacy ]