I'm surprised that patch would have much effect in either direction; it changes the amortization of accounting, but not the actual numbers -- especially for a persistent load. We'll take a look.
<Resend since gmail "reinterpreted" my plain-text> On Fri, Mar 29, 2013 at 4:20 PM, Tim Chen <tim.c.c...@linux.intel.com> wrote: > During our testings of 3.8 kernel, we noticed that after the patch > > Revert "sched: Update_cfs_shares at period edge" (commit 17bc14b7), > > the load between the sockets or larger system can have > large imbalance. For example, for a 4 socket Westmere-EX > (10 cores/socket), we notice the loadings between the sockets > can differ by more than a factor of 4. > > We did a simple experiment that kicks off 29 simple > processes that execute a tight loop. We noticed > socket 3 is already starting to schedule on hyperthreaded cpus > (13 loaded cpus) while socket 1 still have lots of > idle cores (3 loaded cpus). Before the patch, the > load was evenly distributed across sockets. > If I turn off CONFIG_SCHED_AUTOGROUP,the loads are also > distributed evenly. > > (load on cpus, running on 4) > socket 0 1 2 > 3 > --------------------------------------------------------------------------------------------- > cpu: 0-3 0.00 0.00 0.00 > 99.00 > cpu: 4-7 0.00 0.00 0.00 > 99.20 > cpu: 8-11 0.00 0.00 0.00 > 99.00 > cpu: 12-15 99.20 0.00 0.00 > 0.00 > cpu: 16-19 0.00 0.00 0.00 > 99.00 > cpu: 20-23 0.00 0.00 0.00 > 0.00 > cpu: 24-27 0.00 0.00 0.00 > 0.00 > cpu: 28-31 0.00 0.00 0.00 > 0.00 > cpu: 32-35 99.20 0.00 0.00 > 99.00 > cpu: 36-39 99.20 99.40 99.20 > 0.00 > cpu: 40-43 0.00 99.40 99.40 > 99.20 > cpu: 44-47 0.00 99.40 99.40 > 99.20 > cpu: 48-51 99.40 0.00 99.40 > 99.20 > cpu: 52-55 99.20 0.00 99.40 > 99.20 > cpu: 56-59 0.00 0.00 99.40 > 99.40 > cpu: 60-63 0.00 0.00 0.00 > 99.00 > cpu: 64-67 0.00 0.00 0.00 > 99.40 > cpu: 68-71 0.00 0.00 0.00 > 99.40 > cpu: 72-75 99.40 0.00 0.00 > 0.00 > cpu: 76-79 99.40 0.00 0.00 > 0.00 > --------------------------------------------------------------------------------------------- > Loaded cpus 7 3 6 > 13 > > Is this the intended behavior of sched autogroup? I'm a bit surprised > that we are reserving this much cpu bandwidth for very low load > processes (or interactive processes) in other groups. > > So should the sched autogroup config option be turned off by default for > server > system, when we are not concerned about interactivity but want to maximize > throughput by balancing out the load? > > Thanks for clarifying. > > Tim > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
