On Wed, 2 Jan 2008 16:06:20 -0800 "Pallipadi, Venkatesh" <venkatesh.pallipadi@xxxxxxxxx> wrote: > > > >-----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. err, you appear to be suggesting that Mark patch his kernel to make it work as well as 2.6.23? That would be a wrong answer. This regression was known six weeks ago. What do we need to do (or revert) to fix it in 2.6.24? - 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
