>-----Original Message----- >From: Mark Lord [mailto:lkml@xxxxxx] >Sent: Wednesday, January 02, 2008 3:42 PM >To: Arjan van de Ven >Cc: Pallipadi, Venkatesh; Andrew Morton; abelay@xxxxxxxxxx; >lenb@xxxxxxxxxx; Ingo Molnar; linux-kernel@xxxxxxxxxxxxxxx; >linux-acpi@xxxxxxxxxxxxxxx >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@xxxxxx> wrote: >> >>> Arjan van de Ven wrote: >>>> On Fri, 30 Nov 2007 22:14:08 -0500 >>>> Mark Lord <lkml@xxxxxx> 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 ? > Easiest and clean way to do it is to have a driver with set_acceptable_latency() for 1uS or so in init and remove_acceptable_latency() at exit. Thanks, Venki - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
