On Wed, 2014-06-18 at 12:53 +1000, Anton Blanchard wrote: > > I normally wouldn't mind optimizing synthetic cases like this, but a > > quick look at patch 1/3 shows that we're adding an extra overhead (16 > > bytes) in the task_struct. > > > We have the shmmni limit (and friends) for that. > > If we want to use this to guard against the problem, we may need to > drop shmmni. Looking at my notes, I could take down a box with 4096 > segments and 16 threads. This is where I got to before it disappeared: > > # ./bust_shm_exit 4096 16 > # uptime > 03:00:50 up 8 days, 18:05 5 users,load average: 6076.98, 2494.09, 910.37
I win, using 4096 segments and 16 threads: # uptime 13:50:46 up 1 day, 19:41, 2 users, load average: 7621.57, 1718.39, 943.13 13:52:35 up 1 day, 19:43, 2 users, load average: 15422.64, 7409.90, 3156.82 That's on a 16 cpu box running 3.16-rc1. In contrast, if you run it with 1 segment and 16 threads it maxes out about: # uptime 13:58:00 up 1 min, 2 users, load average: 1.81, 0.46, 0.15 And the box is entirely responsive. cheers -- 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/
