>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<< On 11/8/00, 7:15:09 PM, "Remy Maucherat" <[EMAIL PROTECTED]> wrote regarding Re: On what HelloWorldExample performance predicts: > On what HelloWorldExample performance predicts>Roy: Well, not quite: it also > predicts an upper bound on the avg thruput, and a lower >bound bound on the > average response time, of any more resource-intensive request on >the > machine where the resource measurements were taken. > I don't agree with that. > The upper bound to thoughtput would be measured on a servlet which would > output a significant chunk of data (more than 50K, I would say), while not > doing anything else. Remy, I should have said "throughput, as in number of requests processed per second". My point is that if some servlet S requires TC to use more disk+cpu than the HelloWorldExample on a particular machine, then TC's processing rate for S will be lower than it is for the HelloWorldExample. > Hello world outputs a small amount of data (the time > spent parsing the request becomes more significant), and does other stuff in > the process (IO, ...). > The lower bound to response time is a servlet which does nothing. Yes, but the response time for processing HelloWorldExample servlets should be less than the avg response time for processing a servlet S which "does more" than HelloWorldExample. I think we agree, but stated things differently. Or, maybe not :). > How about creating a new "perf" webapp which would contain a selection of > tests ? A kind of synthetic workload? There are commercial products that do that sort of thing, I think. My guess is that, for OS work, it's too difficult to arrange. I think the ab approach is a positive because it allows us to capture information about how TC behaves across a variety of hw/sw environments. It's rough info, but it's potentially consistent, and potentially extensible. I think it's important to design a test to give reasonable information about server response as a function of workload characteristics (resource usage), load, and environment (hw/sw). By this I mean, suppose a potential user HOMER (as in Simpson?)says: I'm thinking of running TC on dual Celeron 400MHz, 256MB SD100 RAM, WD Caviar 10.2MB/5400RPM system. There might be (say) 1500 users on a company Intranet who each make a single request, wait 5 seconds, then make another. 60% of the requests are very simple, kind of like HelloWorldExample, 30% are kind of like ReqInfoExample, and 10% are IO intensive, shoving out 50K each. [Obviously, a very simple scenario: but remember, this is HOMER :-)). HOMER may be interested in some estimate of what the server throughput is likely to be for each type of request, what the server response time is likely to be, and what the CPU and disk utilizations are like (since they might want to put TC on a system with some room for growth). So, I propose a workload model based on servlets we already have (or could develop for). Starements about TC performance are relative to a transportable set of requests and there is no need to get into wars about which version of TC is better. Too simple, I know. This is a bit like what you propose about a "perf" webapp maybe? Roy
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Roy Wilson E-mail:[EMAIL PROTECTED]
