Wireshark-dev: Re: [Wireshark-dev] Enabling linux kernel jit compiler from dumpcap?
2013/8/23 Anders Broman <anders.broman@xxxxxxxxxxxx>:
>> 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@xxxxxxxxxxxxx [mailto:wireshark-dev-bounces@xxxxxxxxxxxxx] On Behalf Of Martin Kaiser
> Sent: den 23 augusti 2013 10:36
> To: wireshark-dev@xxxxxxxxxxxxx
> 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@xxxxxxxxxxxx):
>
>> 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@xxxxxxxxxxxx>:
>>>> Guy Harris skrev 2013-08-22 18:16:
>
>>>>> On Aug 22, 2013, at 4:46 AM, Anders Broman
>>>>> <anders.broman@xxxxxxxxxxxx>
>>>>> 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
>
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