Here are some things we can investigate to gain more information about the current state of the cache:
- Determine what the cache's average hit rate is.
- See how performance varies by increasing the cache size.
- Look into whether YouTube files are blowing out the cache.
- Run a Test Pilot or a smaller experiment to gather user cache data
- In order to gather info on the previous bullet points
Here are some ideas for improving the cache that need to be investigated:
- Consider other eviction options
- Prioritize by file type, giving css and js higher priority
- Evict based on "frecency", not just recency (frequency + recency)
- Use Adaptive Replacement Cache algorithm: http://en.wikipedia.org/wiki/Adaptive_replacement_cache
- We could consider letting servers specify "cache-priority" with resources. This leads to other issues, like fairness.
- Keep dimensions of evicted image files, so layout can still render before the image data arrives across the network
- Compress cache entries?
- This could save space and improve I/O time
- Don't throw away the entire cache when the browser crashes.
And here are some miscellaneous items:
- Add more info to about:cache, including hit rates and other info.
List of Other Cache Resources
Here are some links with other documentation on the cache.
- hacks.mozilla article on revitalizing caching
- My notes on the HTTP cache protocol.
Here is a list of bugs filed on the cache. Many are resolved.
- (http_cache) Meta-bug: improve HTTP cache bug 559729
- Eliminate synchronous reads from cache (make cache reads asynchronous): bug 513008
- Remove sync writes from current cache: bug 513074
- Write/flush cache metadata off main-thread: bug 549767
- xpcshell tests: assertion "mem cache leaking entries" in nsMemoryCacheDevice::Shutdown() causing abort test failed: bug 548406
- Replace necko cache with the Google Chrome cache: bug 514213
- Implement modern cache: bug 512849
- Disk Cache overflow when downloading large files: bug 443067
- Cache corruption when viewing sites with several large images (simultaneous hash collision & cache dooming by disk cache size limit): bug 321361
- Increase default disk cache size: bug 193911
- Figure out the max nr of entries we should store in the disk cache: bug 569709
- Some files are never cached due to hash collisions which are quite common due to weak string hash function: bug 290032
- Need to teach necko to deal with channels reading and writing to a cache entry simultaniously: bug 446876