On 06/09/2021 14:27, Gustaf Ullberg wrote: > Hi Simon and dnsmasq contributors, > > I am running dnsmasq with a blocklist from > https://github.com/notracking/hosts-blocklists/blob/master/dnsmasq/dnsmasq.blacklist.txt > <https://github.com/notracking/hosts-blocklists/blob/master/dnsmasq/dnsmasq.blacklist.txt> > > I have noticed that building dnsmasq with libidn2 support (which my > distro does) can cause extreme slowdowns. The slowdowns seem to come > from the call to idn2_to_ascii_lz in canonicalise() being very slow. > > idn2_to_ascii_lz is run on every domain name in the blocklist to encode > special characters, and this is surprisingly slow even when there are no > special characters. I developed a patch (attached to this email) that > checks a domain name for other characters than . - a-z 0-9. If any such > character is found, the domain name will be encoded. If no such > character is found the domain name will not be encoded (as encoding > won't change it). This removes most of the overhead of using libidn2. > Unless you find any problems with this approach, I wish the patch can be > mainlined. > > Some benchmarks on a Raspberry Pi (slow, but probably not an uncommon > device for running dnsmasq) running ArchLinux and dnsmasq git master: > > # Without libidn2: Acceptable speed >> make >> time ./src/dnsmasq -C dnsmasq.blacklist.txt --test > dnsmasq: syntax check OK. > > real 0m3.699s > user 0m3.468s > sys 0m0.200s > > > > # With libidn2: To slow to be usable >> make COPTS="-DHAVE_LIBIDN2" >> time ./src/dnsmasq -C dnsmasq.blacklist.txt --test > dnsmasq: syntax check OK. > > real 1m6.921s > user 0m59.509s > sys 0m0.606s > > > # With libidn2 and attached patch: Back to acceptable speed >> git am 0001-Avoid-IDN-translations-when-not-needed.patch >> make COPTS="-DHAVE_LIBIDN2" >> time ./src/dnsmasq -C dnsmasq.blacklist.txt --test > dnsmasq: syntax check OK. > > real 0m3.903s > user 0m3.643s > sys 0m0.219s
I see a similar ratio (but much faster absolute execution times) on my Pentium laptop with the latest code. Petr's implementation looks better, but the idea is a good one. Will add to the 2.87 cycle. Cheers, Simon. > > Best regards, > Gustaf > > _______________________________________________ > Dnsmasq-discuss mailing list > Dnsmasq-discuss@lists.thekelleys.org.uk > https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss > _______________________________________________ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss
