Balbir Singh wrote: > Peter Williams wrote: >> Balbir Singh wrote: >> >>> Peter Williams wrote: >>> <snip> >>> >>>>>> But you don't need something as complex as CKRM either. This capping >>>>> >>>>> All CKRM^W Resource Groups does is to group unrelated/related tasks >>>>> to a >>>>> group and apply resource limits. >>>>> >>>>> >>>>>> functionality coupled with (the lamented) PAGG patches (should >>>>>> have been called TAGG for "task aggregation" instead of PAGG for >>>>>> "process aggregation") would allow you to implement a kernel >>>>>> module that could apply caps to arbitrary groups of tasks. >>>>> >>>>> I do not follow how PAGG + this cap feature can be used to put cap of >>>>> related/unrelated tasks. Can you provide little more explanation, >>>>> please. >>>> >>>> >>>> I would have thought it was fairly obvious. PAGG supplies the task >>>> aggregation mechanism, these patches provide per task caps and all >>>> that's needed is the code that marries the two. >>>> >>> >>> The problem is that with per-task caps, if I have a resource group A >>> and I want to limit it to 10%, I need to limit each task in resource >>> group A to 10% (which makes resource groups not so useful). Is my >>> understanding correct? >> >> >> Well the general idea is correct but your maths is wrong. You'd have >> to give each of them a cap somewhere between 10% and 10% divided by >> the number of tasks in group A. Exactly where in that range would >> vary depending on the CPU demand of each task and would need to be >> adjusted dynamically (unless they were very boring tasks whose demands >> were constant over time). >> > > > Hmm.. I thought my math was reasonable (but there is always so much to > learn) > From your formula, if I have 1 task in group A, I need to provide it with > a cap of b/w 10 to 11%. For two tasks, I need to give them b/w 10 to 10.5%. > If I have a hundred, it needs to be b/w 10% and 10.01%
Now your arithmetic is failing you. According to my formula: 1. With one task in group A you give it 10% which is what you get when you divide 10% by one. 2. With two tasks in group A you give them each somewhere between 5% (which is 10% divided by 2) and 10%. If they are equally busy you give them each 5% and if they are not equally busy you give them you give them larger caps. Another, probably a better but more expensive, formula is to divide the 10% between them in proportion to their demand. Being careful not to give any of them a zero cap, of course. I.e. in the two task 10% case they each get 5% if they are equally busy but if one is twice as busy as the other it gets a 6.6% cap and the other gets 3.3% (approximately). Peter -- Dr Peter Williams, Chief Scientist <[EMAIL PROTECTED]> Aurema Pty Limited Level 2, 130 Elizabeth St, Sydney, NSW 2000, Australia Tel:+61 2 9698 2322 Fax:+61 2 9699 9174 http://www.aurema.com _______________________________________________ ckrm-tech mailing list https://lists.sourceforge.net/lists/listinfo/ckrm-tech
