diff --git a/content/screen.sass b/content/screen.sass index 2d4a43f..f7c9d4e 100644 --- a/content/screen.sass +++ b/content/screen.sass @@ -384,6 +384,37 @@ img.feed-icon width: 10em margin: 0 + .seperator + text-align: center + color: #EEE + margin-bottom: 1em + font-size: smaller + + hr + width: 33% + height: 1px + display: inline-block + border: none + background-color: #eeeeee + margin: 5px 0.5em + + &.right + background-image: -webkit-gradient(linear, left center, right center, from(rgb(238, 238, 238)), to(rgb(255, 255, 255))) + background-image: -webkit-linear-gradient(left, rgb(238, 238, 238), rgb(255, 255, 255)) + background-image: -moz-linear-gradient(left, rgb(238, 238, 238), rgb(255, 255, 255)) + background-image: -o-linear-gradient(left, rgb(238, 238, 238), rgb(255, 255, 255)) + background-image: -ms-linear-gradient(left, rgb(238, 238, 238), rgb(255, 255, 255)) + background-image: linear-gradient(left, rgb(238, 238, 238), rgb(255, 255, 255)) + filter: progid:DXImageTransform.Microsoft.gradient(GradientType=1,StartColorStr='#eeeeee', EndColorStr='#ffffff') + + &.left + background-image: -webkit-gradient(linear, right center, left center, from(rgb(238, 238, 238)), to(rgb(255, 255, 255))) + background-image: -webkit-linear-gradient(right, rgb(238, 238, 238), rgb(255, 255, 255)) + background-image: -moz-linear-gradient(right, rgb(238, 238, 238), rgb(255, 255, 255)) + background-image: -o-linear-gradient(right, rgb(238, 238, 238), rgb(255, 255, 255)) + background-image: -ms-linear-gradient(right, rgb(238, 238, 238), rgb(255, 255, 255)) + background-image: linear-gradient(right, rgb(238, 238, 238), rgb(255, 255, 255)) + filter: progid:DXImageTransform.Microsoft.gradient(GradientType=1,StartColorStr='#ffffff', EndColorStr='#eeeeee') table &.left_headers, &.top_headers @@ -420,6 +451,8 @@ table margin: 0 1em 1em 0 + + // Weather body.weather diff --git a/content/technical/2013/01/speed-up-slow-ios-downloads-with-proxy.html b/content/technical/2013/01/speed-up-slow-ios-downloads-with-proxy.html new file mode 100644 index 0000000..d7c4871 --- /dev/null +++ b/content/technical/2013/01/speed-up-slow-ios-downloads-with-proxy.html @@ -0,0 +1,100 @@ +--- +title: Speed Up Slow Downloads on iOS with a Proxy or CDN +extra: How to speed up downloads on iOS. +kind: article +section: technical +created_at: 2013-01-13 12:39:00 +keywords: +- ios +- proxy +- download +- podcast +- squid +- launchd +- cdn +--- + +Whilst developing the Radiopaedia iOS app I ran into the problem of very slow +download speeds within the app. The app has packs of content avaiable for +purchase. The download speed was fine in the simulator but on the device it +was painfully slow. Profiling the code didn't reveal any issues either. + +Some searching revealed people compaining about YouTube videos downloading +faster over 3G than Wi-Fi. There were a number of theories and proposed fixes +for this including: + + * YouTube was sending higher bitrate video when on Wi-Fi + * Checking Wi-Fi access point settings + * Set access point to 802.11b and it goes faster + +At the time I read something that I can no longer find that said that the +iOS Wi-Fi stack has problems when it has a low latency Wi-Fi +connection that is communicating to a comparatively high latency +destination, for example YouTube servers in the US from AU (it +appears there's YouTube end-points in AU these days). From memory I think the +article cited power management under these circumstance as the issue. Howver +since I can't find the original article I might be making that up. + +With this in mind I tested hosting the content packs on an Australian server, +instead of in Amazon S3. This showed a huge improvement in download speed. At +the time Amazon's CloudFront CDN did not have an Australian presence so we +switched to hosting the packs on RackSpace's CloudFiles, which uses the much +more extensive Akamai CDN and ensured that users of the app would have the +best possible download speeds. + +
✦
+ +Fast forward a year or so and I started managing podcasts on my phone instead of +via iTunes. I noticed that some of the podcasts I was subscribed to were horrendously +slow to download. A 100Mb file would take many hours to download, particularly +ones hosted a long way away, such as in the UK or +The Netherlands. I also noted that podcasts that used a CDN downloaded quickly. + +This seemed to be the same problem I had encountered with the Radiopaedia app. +I wondered if telling the iPhone to use a proxy on the local +network would work around the issue. since effectivly move +the destination onto the local network as far as the phone +is concerned (since it will just be talking to the proxy). + +So I set up [Squid][squid] on the Mac mini that's connected to my TV +(using [Homebrew][homebrew]) +since it's always on and has a wired connection to my modem. +I configured the iPhone to use the proxy an lo-and-behold the +very same podcast downloads that were taking hours, now took +minutes. + +[squid]: http://www.squid-cache.org/ +[homebrew]: http://mxcl.github.com/homebrew/ + +To be sure I paused the download, changed the phone's settings +to not use the proxy and restart the download, give it a few +minutes and the estimate was hours. + * Turn the proxy back on and minutes. + +You can see this in action in the screenshots below. The first is not +using the proxy. I have let it download a third of the file to be well +clear [TCP's slow start][slow-start] and it is estimating 57 minutes to +download the remaining 176.1 Mb (53 kb/sec). The second screenshot (only +a minutes later) shows the result after I paused the download, changed +the proxy settings and then again let the download warm up a little. The +estimated time to complete the remaining 143.8 Mb is now only 5 mins +(491 kb/sec) -- a huge improvment. + +[slow-start]: https://en.wikipedia.org/wiki/Slow-start + +
+ Podcast download without proxy +
Podcast download without proxy, 53 kb/sec
+
+ +
+ Podcast download with proxy +
Podcast download with proxy, 491 kb/sec
+
+ +After the successful experiement I left the phone using the proxy and configured +launchd to start squid on boot: + + + + diff --git a/output/images/2013/01/podcast-download-with-proxy.png b/output/images/2013/01/podcast-download-with-proxy.png new file mode 100644 index 0000000..48ceb5a Binary files /dev/null and b/output/images/2013/01/podcast-download-with-proxy.png differ diff --git a/output/images/2013/01/podcast-download-without-proxy.png b/output/images/2013/01/podcast-download-without-proxy.png new file mode 100644 index 0000000..3182c21 Binary files /dev/null and b/output/images/2013/01/podcast-download-without-proxy.png differ