Category: performance

  • asus pn50 and cpufreq/boost

    I’ve been using an ASUS PN50 (that’s a mini pc, with an AMD Ryzen 4800u processor – so sort of a laptop without a screen) as my desktop for ages. Increasingly I’ve found it sluggish and I was contemplating replacing it with something newer, and then I discovered why the CPU speed in /proc/cpuinfo was…

  • faster rsync (ssh cipher choice)

    Perhaps the bottleneck isn’t always bandwidth – but does changing ssh cipher make any difference? Using a derivative of : In unscientific tests, it looks like ssh parameters might do something when copying a 4GiB file between two random virtual machines in different data centres, but both in London. SSH Variant Speed -e “ssh” ~45MB/s…

  • docker proxy image download

    Docker doesn’t like me for some reason, and I often get really bad download speeds from my home IP address. One crude fix, is use an external server I can access as a SOCKS proxy. To do so, edit / create /etc/systemd/system/docker.service.d/http-proxy.conf and put in it : [Service] Environment=”HTTP_PROXY=socks5://localhost:8888″ Then, restart/reload systemd ( systemctl daemon-reload…

  • MySQL Max_connections stuck on 214 ?

    I found MySQL was being annoying earlier and not ‘accepting’ my max_connections = 450 directive on a Debian Wheezy install, and being seemingly stuck on having 214 connections….

  • FTTC limited by wifi….

    Compare : (Speedtest over ethernet) with (Speedtest over wifi). Now how do I go about getting Sky to giving me a wifi router box thing that does 802.11n or whatever?

  • MySQL update/write query analysis (query profiling)

    Do you have a slow MySQL update/insert/delete query? Obviously, for ‘SELECT’ queries you can prepend the query with “EXPLAIN ” – however that doesn’t work for the other query types (UPDATE/INSERT/DELETE). So, one solution which may explain why the query is slow is to turn on MySQL’s profiling functionality, like in the following example :

  • Zend_Cache – automatic cache cleaning can be bad, mmkay?

    $customer uses Zend_Cache in their codebase – and I noticed that every so often a page request would take ~5 seeconds (for no apparent reason), while normally they take < 1 second … Some rummaging and profiling with xdebug showed that some requests looked like : Note how there are 25,000 or so calls for…

  • Checking varnish configuration syntax

    If you’ve updated your varnish server’s configuration, there doesn’t seem to be an equivalent of ‘apachectl configtest’ for it, but you can do : varnishd -C -f /etc/varnish/default.vcl If everything is correct, varnish will then dump out the generated configuration. Otherwise you’ll get an error message pointing you to a specific line number.