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Date: Tue, 1 Jun 2010 20:50:02 -0700
Message-ID: <AANLkTikF-B23_UWG1O3tlBl4m8NStAJllGhhevNhYZT6@mail.gmail.com>
Subject: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8)
From: =?ISO-8859-1?Q?Arve_Hj=F8nnev=E5g?= <arve@android.com>
To: markgross@thegnar.org
Cc: Florian Mickler <florian@mickler.org>, 640e9920@gmail.com,
       "Rafael J. Wysocki" <rjw@sisk.pl>,
       Alan Stern <stern@rowland.harvard.edu>,
       Peter Zijlstra <peterz@infradead.org>,
       Linux PM <linux-pm@lists.linux-foundation.org>,
       Brian Swetland <swetland@google.com>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Matthew Garrett <mjg59@srcf.ucam.org>,
       Thomas Gleixner <tglx@linutronix.de>,
       LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>
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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.

-- 
Arve Hj?nnev?g
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