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Clueless on high TTFB
08-10-2015, 09:15 AM
Post: #4
RE: Clueless on high TTFB
Have you checked opcache is working ( the output of phpinfo() or php --info | grep opcache )?

The secret I've found is to cache everything that possibly can be cached. I don't have experience of linode Tokyo, but do have over many of their other data centres.

Things to check..

- the database. I haven't looksed at Ubuntu lately, but the default configuration used to be completely hopeless. There's a script called that provides a load of info on how that's working. Does this show plenty of resource available? [ you may need to install bc via apt-get first ]
- php memory use. What opcache.memory_consumption values are you using, and memory_limit?
- swap use. This should be zero if at all possible! You can help that by setting vm.swappiness to a low value - say 10 in /etc/sysctl.conf
- Is DNS resolving quickly? Do you have a local 'caching nameserver' in use that the system is set up to interrogate first?

Because most of the database traffic for a website is reading, not writing/updating, use of a database cache ( these days the innodb engine should be used exclusively really, so it's those caches I'm talking about primarily ) will dramatically speed up a site as info can just be delivered directly from memory.

If you're having DNS resloution issues, then the system load will be frustratingly low at the same time as your performance. If you run something like top ( I recommend the alternative htop as it provides more info for me at least ), then you'll be able to see the base loading on the system when you're looking at your web pages. [ I've just read Sp0ck's post, and I'm duplicating what he's said in effect ].

I'd say that one of these two may well be at the core of the TTFB problems ( which are 99% certainly infrastructure based ), and once they are fixed, you can look at opcode, etc caching and other performance enhancements. It's normal to find that the ultimate bottleneck for a PHP CMS based website is the raw CPU power that PHP needs. Once you're there, it's time to upgrade!
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Clueless on high TTFB - Sp0cK - 08-03-2015, 12:27 PM
RE: Clueless on high TTFB - pmeenan - 08-04-2015, 12:26 AM
RE: Clueless on high TTFB - Sp0cK - 08-04-2015, 12:53 AM
RE: Clueless on high TTFB - GreenGecko - 08-10-2015 09:15 AM

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