Planet WYLUG

• @xbaz us too! now i have to walk to the shop before i can have my cereal. boo. in reply to xbaz #
• can’t wait until her desk and printer are in the same room, not two floors apart. #
• loves the smell of wet cat. #notaeuphemism #
• suspects she’ll be upgrading her OS this evening. what fun! #
• changes her application and desktop fonts to comic sans just to see @johnleach grimace #
• is trying to get used to her long-awaited ubuntu upgrade - suspect i won’t notice the changes that benefit me, just the annoying niggles #
• has her bookmarks from a year ago instead of her current list after an upgrade snafu. funny how much it’s changed. #
• adds twister ice lollies into the deliciousness hall of fame, alongside vimto and encona sauce. #
• is waiting, impatiently. #
• is now riding a giant wave of frustration. #
• worked out her frustration by trimming the fuchsia bush. trimming it with a big saw. #
• has not found any mindmapping/brainstorming software that comes close to beating a pencil and big piece of paper. #
• feels cleaner after restyling a messy document. #
• finds it very strange writing formal, serious work-related emails to people she’s met socially #
• is decidedly unimpressed with lloyds tsb fraud prevention efforts. #
• had a charity shop win. took 6 bags of stuff in & got a complete set of ugly-ace 1970s crockery, which matches our existing set, for £3.80. #
• got a tshirt&comic from liz prince (http://lizprincepower.com/) the other day. post from an internet famous person! http://twitpic.com/8kquw #
• “enjoyed” a modern day re-enactment of Romeo & Juliet last night between two drunk, repugnant neighbours. #
• That rock through yonder window breaks. It is my house and Juliet has locked the door…. #
• … Arise, fair Armley, and kill the ugly bitch. Who is already sick and pale with hangover. #
• [POLICE enter. ROMEO is manhandled into a police car. Exit] #
• declares the ankle to be the funny bone of the foot, ie, it hurts disproportionately when you bang it. #
• has spent years trying to woo @johnleach with intellectual humour & wonderpuns but made him laugh more than ever today with a silly walk. #

(As originally posted on my Twitter thingy.)

louisa_ “enjoyed” a modern day re-enactment of Romeo & Juliet last night between two drunk, repugnant neighbours.

ROMEO: That rock through yonder window breaks.
It is my house and Juliet has locked the door.
Arise, fair Armley, and kill the ugly bitch.
Who is already sick and pale with hangover.

[POLICE enter. ROMEO is manhandled into a police car. Exit]

(This follows on from last year’s “Summer in Armley” post.)

• is delighted that for the first time in nearly 4 years, she doesn’t have to read any tabloid newspapers for work today. hoorah for change. #
• doesn’t mind thunder but dislikes lightening. after years in a dark house with @johnleach, super loud noises don’t scare me but light, eeek! #
• dries her cat after he, evidently, chose to stay out in the rain. #
• has had an interesting evening but shall leave it at that for now because it’s so much fun keeping Katherine in suspense. ;) #
• is glad she woke up fractionally before the pneumatic drill started. #
• and @johnleach have a new streetlight outside their house - will be strange for nights to be white-lit, after a lifetime of orange. #
• tends the oregano, basil, mint and rosemary growing in the garden - my hands now smell great :) #
• now has hands smelling of vinegar rather than herbs - shiny clean (albeit a little streaky) windows though! #
• hopes to fall asleep before the caffeine from her ill-advised evening cup of tea kicks in. had it with good cake though. #
• starts the day doing something she usually leaves until last - wonder how that will affect procrastination/productivity… #
• watches a magpie eating cat food left out for the stray cat. Sili’s watching too and imagining a cat food-filled bird - chirp! chirp! #
• would like to know how SEOers justify charging a monthly fee for a site with static content. not being aggressive, I’d really like to know. #
• saved 12p on a tshirt order from the US because of an exchange rate change between adding it to my cart & buying it 2 days later. score! ;) #
• is frustrated: in the last few weeks, I’ve tried to offer two companies my b2b custom but they have no contact details on their websites. #
• had an awesome time at GeekUp. Talked about absolutely everything and put the world to rights. Solution to all problems: I’m put in charge. #
• listened to her snooze alarm beeping for 40 minutes then had to eat her cereal in the car. #
• @IdleSi yep, http://tinyurl.com/bradford-listed - i had it bookmarked because we nearly bought one ;) in reply to IdleSi #
• watches a big cat lapping milk in time with @johnleach’s ukelele playing - they finish at the same time too. #
• is going for curry. hurrah! #
• and @johnleach are going to look around their new house again today. excited! excited! #
• is now even more excited about the new house now. we’ll have windows! and trees! and secret cupboards! and secret windows! #
• and @johnleach have a new cunning idea that could make the new house even more exciting and awesome. perhaps too exciting. #
• @Squiggle ok, now we have two possibly too exciting ideas for the new house. ;) in reply to Squiggle #
• is having her first Sunday off in 3.5+ years. been to the farmers’ market and the pub so far - wonderful. #

On a busy Linux Netfilter-based firewall, you usually need to up the maximum number of allowed tracked connections (or new connections will be denied and you’ll see log messages from the kernel link this: nf_conntrack: table full, dropping packet.

More connections will use more RAM, but how much?  We don’t want to overcommit, as the connection tracker uses unswappable memory and things will blow up. If we set aside 512MB for connection tracking, how many concurrent connections can we track?

There is some Netfilter documentation on wallfire.org, but it’s quite old. How can we be sure it’s still correct without completely understanding the Netfilter code? Does it account for real life constraints such as page size, or is it just derived from looking at the code? A running Linux kernel gives us all the info we need through it’s slabinfo proc file.

We can peek at how the kernel is using RAM using the proc file /proc/slabinfo and clear this up.  The nf_conntrack entry from here tells us, on one particular firewall, that there are 26,702 active entries (or objects), that each object is 304 bytes in size and 13 of them fit in each slab (and that each slab is 1 kernel page).  So we know that conntrack entries take up 304 bytes each.  But if we’re going to be accurate, then we have to account for the overhead of the kernel page size.

The Linux kernel uses a slab memory allocator, so rather than allocating 304 bytes every time a conntrack entry is needed, they are allocated in “slabs” of one or more kernel pages which reduces memory fragmentation and improve performance.  When they’re done with, they’re not immediately freed - instead the memory is reused the next time another object of the same type is needed.

In the kernel we’re using, the page size is 4096 bytes. As slabinfo told us, 13 nf_conntrack objects fit in each slab and each slab takes up 1 page. 13 objects of 304 bytes is 3952 bytes in total, which leaves 144 bytes of waste per slab.  So every 13 objects we waste 144 bytes. So a nf_conntrack object consumes about 316 bytes on this box, giving us almost 1.7 million entries for our 512MB.

You can get your kernel’s page size with the command: getconf PAGESIZE. The slabtop program, installed on most modern GNU/Linuxes, shows the info from /proc/slabinfo it in a pretty table and lets you sort the values.

Greetings from Philadelphia!  I am presenting as part of the IPv6 at NANOG46 (click here for info of how to watch) at 9:30PM UK time today, or download the IPv6 for Enterprises presentation here, or see information about the other speakers here..

The messages are clear and simple.  Working now to get ready for the IPv6 transition will be less expensive and lower risk than waiting for IPv4 starvation to hurt.  I interviewed some key enterprises about their specific grumbles but the great news is that most are transitional and already people are working on fixing them.

• discovers an ink blotch on her forearm from last night’s late night diary writing. #
• listens to @johnleach make cereal/serial jokes. is not amused. #
• is presently particularly partial to pickled peppers. #
• has crossed everything off her to-do list for today and @johnleach is making paneer and chickpea curry for tea: double win! #
• had a lovely meal at Cooper’s in Guiseley with Katherine. Had a bad driving lesson before then: better driving backwards than forwards now. #
• dreamt of salty sea dogs. #
• can’t wait to be working in our new office in the new house - craving music and space. #
• reads some comments that don’t help her mood one bit, even though she knows the remarks are just trolling. sigh. #
• feeds the cats a big pile of meat to celebrate it being 10yrs since Carla, Carbon & I adopted each other. Gave a short unappreciated speech. #
• had a surreal 1930s themed trip to the cinema this evening. Probably ate more crap than they did in the 1930s, laughed more too. #
• got “chased” by two horses on the way to the hairdressers - they were running, I wasn’t. i will miss armley. #
• had to bite her tongue several times at the hairdressers. Everyone repeating myths about nutrition, diet & sex education as the truth. sigh. #
• hasn’t done as much work as she should have done this afternoon but nevermind. been a good, busy week all in all. time to sit in the sun. #
• had a lovely day in Harrogate with @johnleach. ate lemon & lime cheesecake and bought binoculars from oxfam & fabric for bunting. #
• can smell the neighbours’ bbqs and now has super-mad bbq cravings. #
• is having to work today because PastLouisa_ was slack on Friday but is getting ahead on some stuff too so FutureLouisa_ likes her tomorrow. #
• has another wonderfully long conversation with @johnleach & @thattommyhall. world not put to rights, just decided everyone is confused. #

• woke up feeling perfectly rested this morning. a novel experience. #
• finally gave Recycle This the long, long, awaited redesign that it very much needed. New features to follow. http://www.recyclethis.co.uk/ #
• has a re-pinkened arm after a driving lesson and wonders if having a truckers’ tan will help her pass her test. #
• wonders how she could implement blog-style tags in her offline pen & paper diary for easier categorisation/browsing… any suggestions? #
• thought maybe coloured tabs in specific positions on the side of pages would work - would limit the max. number of tags but that might be ok #
• woke up two minutes before her alarm for the second time in a row this morning, very strange. #
• is too hot to be proactive at the moment. #
• spent the afternoon doing some quite major pruning in the garden. got a blister and very very sticky. showered now and feel ace. #
• is keen to point out at @johnleach was not being euphemistic in this tweet - http://twitter.com/johnleach/status/2007077575 #
• watches a cat trying out different plantpots for size: “this is a little small but the foliage is more cushioning than in the other one”. #
• feels like screaming. #
• wonders which will break first @johnleach or her unicycle. #
• thinks it’ll be both, at the same time, spectacularly. probably a good thing i don’t want to have children too. #
• is glad the afternoon is ending on a high note - some great news after hours and hours of stress. #
• @tim_waters we’ve got an 850W and all the instructions i read are for 800W. perhaps we should swap food. in reply to tim_waters #
• hasn’t drunk nearly enough liquid today. my brain feels like a raisin. #
• is feeling strangely low despite an awesome lunch and it being the weekend tomorrow. swimming this afternoon though. #
• can smell rice. mmm. #
• enjoyed fish & chips with @johnleach in horsforth park last night then went to @thattommyhall’s for tea, wombling & discussion of everything #
• is listening to @johnleach serenading the cooking sausages with his ukelele & falsetto vocals. a day of nothingness awaits, hurrah. #
• is stuffed after a lovely meal at little tokyo. should do something productive this evening but probably won’t. #

Tim Dobson very kindly recorded and uploaded my talk on the Ukepedia at Barcamp Leeds last Saturday.

For those of your with short attention spans, I finally get started with the talk at about 2mins 30, and start singing the first article, Otitis Media, at about 7mins.

“Internet Explorer 8 is the latest version of the familiar web browser you are most comfortable using…”

Well, its not and that is a fair bit of assumption on your part, dear Microsoft. Doesn’t mean I won’t install it though as its better than all the ones that have gone before it so I’ll give you that. That and you seem to be understanding that the word Standard means something that everyone agrees on, not just you.

That still doesn’t stop me installing Firefox on all the Windows servers I manage however, no matter how much your “hardened” IE configuration doesn’t play with Mozilla’s GEOIP-based mirror system thingy. Yeah, I end up at the command line doing an mget from mirrorservice.org…

Pretty much ever since we launched (How Can I) Recycle This three years ago, I’ve been wanting to redesign it - to freshen it up and to make better use of the available space.

I finally got around to doing it last month and with John’s help, we launched the new design on Sunday (and moved it onto being hosted on Brightbox).

I’ve got loads of ideas for new features - and finally got some space to fit them on the page now. Just got to find the time to implement them now…