iana-etc with STRIP=yes

Dan Nicholson dbn.lists at gmail.com
Tue Oct 7 09:05:44 PDT 2008


On Tue, Oct 7, 2008 at 8:54 AM, Randy McMurchy
<randy at linuxfromscratch.org> wrote:
> Valter Douglas Lisbôa Jr. wrote:
>> Not a major issue, but a recent thread shows using the make STRIP=yes on
>> iana-etc to cut out comments and accelerate the port search on port
>> resolution. In the new LSF does  anyone remember to put this on the book?
>
> Not sure about the "accelerate the port search on port resolution".
> Here's a quote from Seth's (the maintainer) site:
>
>     To throw out the useful comments in generated files (useful for embedded
>     installations), use:
>
>        make STRIP=yes
>
>
> He doesn't mention anything about acceleration. He says it's
> useful for embedded systems. Do you have a URL of this thread?

Whenever you do a getservbyname(), the glibc resolver has to parse out
/etc/services. This happens when you use "http", and the resolver has
to decide what port number to use. Likewise, when some program
specifies "tcp", the glibc resolver has to parse /etc/protocols to
decide what protocol number that corresponds to. So, cutting out the
comments just makes the parsing faster. I saw a discussion of this a
while ago on a fedora list, but I can't find the link now.

You can test this yourself with getent and then try again with a
stripped down /etc/services (I didn't bother).

$ time { for ((n = 0; n < 100; n++)); do getent services http
>/dev/null; done; }

real    0m0.098s
user    0m0.033s
sys     0m0.065s

I happen to think the comments are more beneficial than any speedup,
but that's just my preference.

--
Dan


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