On 12/23/2010 10:08 AM, Zirui wrote:
Hi guys, I have installed ATS-2.0.1 and done some stress test with web polygraph. I found a interesting thing that when I set server sending 100% cachable objects and client to made 50% revisit to the url it has visited, object size is about 15KB. Both ATS and Squid have perfect hit rate. However, squid runs faster because it has many TCP_MEM_HIT meanwhile ATS seems always read&write disks (cache.db). I used systemtap to trace traffic_server and found I/O on cache.db about 10MB/s, which is considerable on my SATA disk. Squid seldom reads or writes disk. I am sure I modified following config: proxy.config.cache.ram_cache.size 536870912 Disk cache is 1GB. Is there any other thing I have to change to enable ATS utilize more memory?
That should do it (you have it right, in that you need both a disk cache and RAM cache). The one thing I can think of is that objects don't get promoted to RAM cache directly, so if you only hit the object twice, you wouldn't see any RAM cache hits I think.
Assuming however that you are hitting each objects more than twice, I'm not sure what is going on. Is there any chance you can try v2.1.4 instead and see if the same problem occurs there ?
-- Leif
