for question #1: proxy.config.http.record_tcp_mem_hit will help you get a TCP_MEM_HIT in the squid log of trafficserver.
FYI 在 2011-08-09二的 12:55 -0600，Leif Hedstrom写道： > On 08/09/2011 12:38 PM, Karri Vrkreddy wrote: > > Hi, > > We are using ATS as reverse proxy. > > In our use case most of the data is dynamic ( responses from the > > backend hosts ) and need not be cached for more than 5-10 mins. > > > > We currently configured it to have a disk cache size of 10 GB and we > > left the proxy.config.cache.ram_cache.size as -1. So that would give us a > > ram cache size of 10 MB. > > Here are my questions : > > > > 1. Since the ram cache size is very small, does a TCP_HIT mean a disk > > access ? ( this is a 16 GB node and lots of free memory, so I mostly > > buffer cache plays a > > I don't think we distinguish between RAM vs disk cache in the squid > logs, I'm not even sure it's possible to configure a log that does it > either. In fact, I think there was an RFE to add such log data. > > However, you can certainly see how much RAM cache hit ratio vs disk > cache hit ratio you get, in the stats. That's not per request though. > > 10MB seems like an *incredibly* small RAM cache. Make it bigger ;). > > > significant role ) > > 2. Given the nature of the data ( not required to cache for more than > > 10 min ), any specific suggestions to make ATS more efficient ? > > Well, with such a small cache, 10GB, I'd spend a few hundred $'s and put > it on SSD. It'll make it wicked fast. To use the cache efficiently, tune > the minimum object size setting (in records.config) to be close to your > average / typical size. The default is 8K, which is fairly reasonable, > but if your objects are significantly bigger (or smaller) than this, > you'll use the cache more efficiently by tuning it. > > > 3. As far as I can understand from the documentation, it looks like > > only highly used objects will go to Ram Cache. According to that in our use > > case only few will > > it there. Any tweaks or change in algorithms to move as much as > > possible to Ram Cache. > > It will only keep the "most used" objects in RAM cache. With such a > small RAM cache as yours, that's probably very few objects, and you are > more likely to suffer from cache evictions happening much more frequent > than you'd want. Again, you ought to have a bigger RAM cache, I mean, a > couple of gig RAM today is like 50 bucks. > > If memory is truly a scarce resource, you can try to enable the > compression feature on the RAM. It can save some memory on objects that > are not already gzip'ed. > > > Cheers, > > -- Leif >
