The benefit of write-through to main memory is that it simplifies the design of the computer system. With write-through, the main memory always has an up-to-date copy of the line. So when a read is done, main memory can always reply with the requested data. If write-back is used, sometimes the up-to-date data is in … Read more
Redis is a remote data structure server. It is certainly slower than just storing the data in local memory (since it involves socket roundtrips to fetch/store the data). However, it also brings some interesting properties: Redis can be accessed by all the processes of your applications, possibly running on several nodes (something local memory cannot … Read more
I believe that must-revalidate means : Once the cache expires, refuse to return stale responses to the user even if they say that stale responses are acceptable. Whereas no-cache implies : must-revalidate plus the fact the response becomes stale right away. If a response is cacheable for 10 seconds, then must-revalidate kicks in after 10 … Read more
I had the same issue when upgrading from Tomcat 7 to 8: a continuous large flood of log warnings about cache. 1. Short Answer Add this within the Context xml element of your $CATALINA_BASE/conf/context.xml: <!– The default value is 10240 kbytes, even when not added to context.xml. So increase it high enough, until the problem … Read more
This solution is written in PHP, but it should be easily adapted to other languages. The original .htaccess regex can cause problems with files like json-1.3.js. The solution is to only rewrite if there are exactly 10 digits at the end. (Because 10 digits covers all timestamps from 9/9/2001 to 11/20/2286.) First, we use the … Read more
TL;DR There is an analogy with a cold engine and warm engine of the car. Cold cache – doesn’t have any values and can’t give you any speedup because, well, it’s empty. Warm cache has some values and can give you that speedup. A cache is a structure that holds some values (inodes, memory pages, … Read more
There is a common pattern that solves this problem quite well. Use sorted sets, and use a timestamp as the score. It’s then trivial to delete items by score range, which could be done periodically, or only on every write, with reads always ignoring the out of range elements, by reading only a range of … Read more
At this level of detail, you have to break “the cache” and “the TLB” down into their component parts. They’re very tightly interconnected in a design that uses the VIPT speed hack of translating in parallel with tag fetch (i.e. taking advantage of the index bits all being below the page offset and thus being … Read more
The cache is there to reduce the number of times the CPU would stall waiting for a memory request to be fulfilled (avoiding the memory latency), and as a second effect, possibly to reduce the overall amount of data that needs to be transfered (preserving memory bandwidth). Techniques for avoiding suffering from memory fetch latency … Read more
Make sure you have the disable cache checkbox unchecked/disabled in the Developer Tools.