Srivatsa Vaddagiri wrote: > Here's an attempt to extend CFS (v13) to be fair at a group level, rather than > just at task level. The patch is in a very premature state (passes > simple tests, smp load balance not supported yet) at this point. I am sending > it out early to know if this is a good direction to proceed. > > Salient points which needs discussion: > > 1. This patch reuses CFS core to achieve fairness at group level also. > > To make this possible, CFS core has been abstracted to deal with generic > schedulable "entities" (tasks, users etc). > > 2. The per-cpu rb-tree has been split to be per-group per-cpu. > > schedule() now becomes two step on every cpu : pick a group first (from > group rb-tree) and a task within that group next (from that group's task > rb-tree) > > 3. Grouping mechanism - I have used 'uid' as the basis of grouping for > timebeing (since that grouping concept is already in mainline today). > The patch can be adapted to a more generic process grouping mechanism > (like http://lkml.org/lkml/2007/4/27/146) later. > > Some results below, obtained on a 4way (with HT) Intel Xeon box. All > number are reflective of single CPU performance (tests were forced to > run on single cpu since load balance is not yet supported). > > > uid "vatsa" uid "guest" > (make -s -j4 bzImage) (make -s -j20 bzImage) > > 2.6.22-rc1 772.02 sec 497.42 sec (real) > 2.6.22-rc1+cfs-v13 780.62 sec 478.35 sec (real) > 2.6.22-rc1+cfs-v13+this patch 776.36 sec 776.68 sec (real)
This would seem to indicate that being fair between groups isn't always a good thing. With 2.6.22-rc1 and 2.6.22-rc1+cfs-v13 "guest" gets his build done in about 2/3 the time of "vatsa" without seriously inconveniencing "vatsa". All making scheduling fair between the groups has done is penalize "guest" without significantly improving matters for "vatsa" (he gains a mere 4 seconds out of 780). BUT I imagine that this is an artefact caused by the use of HT technology and that if the test were run on a computer without HT the results would be more impressive. Peter -- Peter Williams [EMAIL PROTECTED] "Learning, n. The kind of ignorance distinguishing the studious." -- Ambrose Bierce ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ ckrm-tech mailing list https://lists.sourceforge.net/lists/listinfo/ckrm-tech
