On 01/29/2014 07:08 AM, Kinkie wrote: > Amos has asked me over IRC to investigate any performance > differences between Vector and std::vector. To do that, I've > implemented astd::vector-based implementation of Vector > (feature-branch: lp:~squid/squid/vector-to-stdvector).
Does Launchpad offer a way of generating a merge patch/diff on the site? Currently, I have to checkout the branch and do "bzr send" to get the right diff. Is there a better way? > I've then done the performance testing using ab. The results are in: a > Vector-based squid is about 3% speedier than a std::vector based > squid. > This may also be due to some egregious layering by users of Vector. I > have seen things which I would like to correct, also with the > objective of having Vector implement the same exact API as std::vector > to make future porting easier. Can you give any specific examples of the code change that you would attribute to a loss of performance when using std::vector? I did not notice any obvious cases, but I did not look closely. > test conditions: > - done on rs-ubuntu-saucy-perf (4-core VM, 4 Gb RAM) > - testing with ab. 1m requests @10 parallelism with keepalive, > stressing the TCP_MEM_HIT code path on a cold cache > - test on a multicore VM; default out-of-the-box configuration, ab > running on same hardware over the loopback interface. > - immediately after ab exits, collect counters (mgr:counters) > > numbers (for trunk / stdvector) > - mean response time: 1.032/1.060ms > - req/sec: 9685/9430 > - cpu_time: 102.878167/106.013725 I hate to be the one asking this, but with so many red flags in the testing methodology, are you reasonably sure that the 0.28 millisecond difference does not include 0.29+ milliseconds of noise? At the very least, do you consistently get the same set of numbers when repeating the two tests in random order? BTW, your req/sec line is redundant. In your best-effort test, the proxy response time determines the offered request rate: 9685/9430 = 1.027 (your "3% speedier") 1.060/1.032 = 1.027 (your "3% speedier") 10*(1000/1.032) = 9690 (10-robot request rate from response time) 10*(1000/1.060) = 9434 (10-robot request rate from response time) Cheers, Alex.
