5 ms·
When I worked on a large CDN the content popularity distribution was heavily skewed. Think 20-40% of throughput from top 1% if content, and 80-90% from the top
by donavanm 14d ago
When I worked on a large CDN the content popularity distribution was heavily skewed. Think 20-40% of throughput from top 1% if content, and 80-90% from the top 10%. Anything outside of that had a very low probability if ever being read again in the effective cache lifetime.
Then the effective cost of scaling CPU > RAM > storage > network due to power & space limitations. Spending extra processing time on 50% of your content would be wasted effort as its never read again.
And yes, increasing effective storage might increase cache width/lifetime, but its not by that much to dramatically inprove access rates. Especially when most content by unique bytes is compressed audio/video in the first place.
- im3w1l 13d agoYou are making an argument against caching it at all which is clearly not what they want. So the comparison must be uncompressed storage vs compressed storage. The compression cost is always the same. The storage cost depends on how long you keep something in cache. The decode cost is proportional to number of total hits. So compression makes the most sense for something you want to keep a long time that will be accessed very rarely. And the least sense for something you will drop very soon and will have many people requesting it.
- donavanm 12d agoMaybe cloudflares workload is substantially different, but i think youre missing just how long that tail was. A “lot”, maybe half, of unique objects werent requested a second time in any meaningful period time. Like days. And edge nodes have nowhere near the iops or cycles to spend doing _any_ extra work. So yes it is a waste of resources to cache or process in any way.