Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8) | Date | Thu, 3 Jun 2010 23:02:59 +0200 |
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On Thursday 03 June 2010, mark gross wrote: > On Thu, Jun 03, 2010 at 12:03:49AM +0200, Rafael J. Wysocki wrote: > > On Wednesday 02 June 2010, mark gross wrote: > > > On Tue, Jun 01, 2010 at 08:50:02PM -0700, Arve Hjønnevåg wrote: > > > > On Tue, Jun 1, 2010 at 7:05 AM, mark gross <640e9920@gmail.com> wrote: > > > > > On Tue, Jun 01, 2010 at 09:07:37AM +0200, Florian Mickler wrote: > > > > ... > > > > >> +static void update_target_val(int pm_qos_class, s32 val) > > > > >> +{ > > > > >> + s32 extreme_value; > > > > >> + s32 new_value; > > > > >> + extreme_value = atomic_read(&pm_qos_array[pm_qos_class]->target_value); > > > > >> + new_value = pm_qos_array[pm_qos_class]->comparitor(val,extreme_value); > > > > >> + if (extreme_value != new_value) > > > > >> + atomic_set(&pm_qos_array[pm_qos_class]->target_value,new_value); > > > > >> +} > > > > >> + > > > > > > > > > > Only works 1/2 the time, but I like the idea! > > > > > It fails to get the righ answer when constraints are reduced. But, this > > > > > idea is a good improvement i'll roll into the next pm_qos update! > > > > > > > > > > > > > I think it would be a better idea to track your constraints with a > > > > sorted data structure. That way you can to better than O(n) for both > > > > directions. If you have a lot of constraints with the same value, it > > > > may even be worthwhile to have a two stage structure where for > > > > instance you use a rbtree for the unique values and list for identical > > > > constraints. > > > > > > I don't agree, we went through this tree vrs list discussion a few times > > > before in other areas of the kernel. Wherever the list tended to be > > > short, a simple list wins. However; we can try it, after we have some > > > metrics and stress test cases identified we can measure its effectivenes > > > against. > > > > How many different values are there to handle? > > > > for the current pm_qos users its tiny. I've never heard of more than a > few < 10. However; for the new "interactive" class to provide suspend > blocker functionality, I expect the number to be up to 20. > > but realistically I bet we never get more than 10ish. > > One constraint constraint request per module from isr to user mode. > Once in user mode there would be only a few (assuming Android user > space) I think just from the power HAL, input HAL, and the RIL. > > Still a pretty small number I don't think we need to worry about scaling > as much as we need to worry about performance.
In that case sorting the structure is rather not going to improve things, but it might be worth using a hashtable or something similar.
Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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