On 01/29/2014 02:32 PM, Kinkie wrote: > On Wed, Jan 29, 2014 at 7:52 PM, Alex Rousskov wrote: >> On 01/29/2014 07:08 AM, Kinkie wrote:
> (in a trunk checkout) > bzr diff -r lp:/squid/squid/vector-to-stdvector > > The resulting diff is reversed, but that should be easy enough to manage. Thanks! Not sure whether reversing a diff in my head is easier than downloading the branch :-(. >> 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. > I suspect that it's all those lines doing vector.items[accessor] and > thus using C-style unchecked accesses. std::vector[] element access operator does not check anything either, as we discussed earlier. IIRC, you [correctly] used a few std::vector::at() calls as well, but I did not see any in a critical performance path. >>> 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 >>> - cpu_time: 102.878167/106.013725 > If you can suggest a more thorough set of commands using the rough > tools I have, I'll gladly run them. How about repeating the same pair of tests a few times, in random order? Do you get consistent results? Thank you, Alex.
