Messages in this thread | | | Date | Wed, 02 Jan 2008 18:41:55 -0500 | From | Mark Lord <> | Subject | Re: + restore-missing-sysfs-max_cstate-attr.patch added to -mm tree |
| |
Arjan van de Ven wrote: > On Fri, 30 Nov 2007 22:31:17 -0500 > Mark Lord <lkml@rtr.ca> wrote: > >> Arjan van de Ven wrote: >>> On Fri, 30 Nov 2007 22:14:08 -0500 >>> Mark Lord <lkml@rtr.ca> wrote: >>> >>>>> in -mm there is.. the QoS stuff allows you to set maximum >>>>> tolerable >>>> .. >>>> >>>> That's encouraging, I think, but not for 2.6.24. >>>> >>>>> latency. If your app cant take any latency, you should set >>>>> those... and the side effect is that the kernel will not do >>>>> long-latency C-states or P-state transitions.. >>>> .. >>>> >>>> I don't mind the cpufreq changing (actually, I want it to drop in >>>> cpugfreq to save power and keep the fan off), but the C-states just >>>> kill this app. >>>> >>>> The app is VMware. I force the max_state=1 when launching, >>> ah but then its' even easier... and can be done in 2.6.24 already. >>> VMWare after all has a kernel module, and the latency stuff is in >>> 2.6.23 and 2.6.24 available inside the kernel already. >> .. >> >> Oh, I'm perfectly happy to write my own kernel module if that's what > > all you need to do in your kernel module is call > > add_latency_constraint("mark_wants_his_mouse", 5); > > or so ..
Dredging up an old regression again now:
The "make my own module to replace /sys/.../max_cstate" doesn't work for the single-core machine we use a lot around here.
VMware is totally sluggish unless I go to another text window and do this:
while ( true ); do echo -n ; done
At which point VMware performs well again, the same as with "echo 1 > max_cstate" in 2.6.23.
Anyone got any suggestions on how to fix this regression or work around it for 2.6.24 ?
Thanks
| |