Messages in this thread | | | From | "Doug Smythies" <> | Subject | RE: [ 11/37] sched/nohz: Rewrite and fix load-avg computation -- again | Date | Sat, 21 Jul 2012 09:02:21 -0700 |
| |
> On 2012.07.20 10:26 -0700, Peter Zijlstra wrote: >> On Fri, 2012-07-20 at 12:13 -0500, Jonathan Nieder wrote: >> > Peter Zijlstra wrote: >> >> On Tue, 2012-07-17 at 19:16 -0500, Jonathan Nieder wrote: >> >> >> I'm thrilled to see this regression fix for stable@, but are we really >> >> really sure that it won't cause new regressions? >> > >> > Doug Smythies ran a ~68 hour test on it, running various synthetic loads >> > of various frequencies against it and comparing the reported load >> > averages against the expected values and found it to be 'good'. >> > >> > This doesn't guarantee we won't find more 'interesting' problems in >> > there, but it does give me fair confidence in it. >> >> Yeah, that sounds good. Very nice to hear. >> >> Is the code to generate the synthetic loads and expected results >> somewhere easy to find (like LTP or tools/testing) to make it easier >> to keep this code working well in the future?
> /me finds Doug isn't actually on the CC, /me fixes.
Thanks.
> Doug had this web-page with all his testing activities, graphs and code > etc.. > http://www.smythies.com/~doug/network/load_average/ > Seems to still work.
Those web pages will be there for a long time (years).
> Last time I tried his scripts they weren't very user friendly, and afaik > he's making the pretty graphs 'manually'. But whatever he's got is there > I think.
Yes, pretty graphs were manually done. Yes, scripts lack user friendliness, but everything I used is posted.
> If someone wants to take it and make it pretty and 'usable' for people > in a hurry I'm sure Doug wouldn't mind.
Someday I might make it more useable myself. Peter's "consume.c" is very useful also. (I haven't posted it in my web notes yet, but I will.)
The 68 hour test was just one of the tests runs, albeit the main one. Among the other tests was what I call the "Charles Wang" scenario, high frequency high loads.
The only operating scenario of potential concern was around higher loads higher number of processes, where the reported load average Was a little low and worse than the same conditions without this patch, although still pretty good (graph attached).
[unhandled content-type:image/png]
| |