Hi All, Blaisorblade <[email protected]> [20050927 18:51:36 +0200]: > > On Saturday 10 September 2005 16:01, Alexander Clouter wrote: > > Hi, > Summary for Andrew Morton: > > ondemand's ignore_nice attribute has a reversed meaning, and fixing this > requires changing the API for the user playing with sysfs. Thus, it should be > fixed ASAP, i.e. 2.6.14. > > echo 0 > /sys/devices/system/cpu/cpu0/cpufreq/ondemand/ignore_nice > Then ondemand ignores nice tasks when calculating CPU load. > echo 1 > /sys/devices/system/cpu/cpu0/cpufreq/ondemand/ignore_nice > Then ondemand considers nice tasks when calculating CPU load. > > It's the reverse of the expected behaviour, even Alexander Clouter got > confused on it when I first reported this bug. > > So I suggest: > *) to flip the flag's behaviour, as discussed with Alexander > > *) to rename the flag to ignore_nice_load or ignore_nice_tasks, to avoid > burning the user too much. Very few people use it now, but let's help them. > > *) Alexander had a piece of doc he wrote about all this and sent me, it'd be > nice to have this merged too. > > Alexander (quoted near the end) said to have rolled the patches, but they're > lost somewhere, don't know if he forgot or they're in some staging tree > in-the-middle. I guess I could roll up the patches if needed, but this week > I'm really busy, so probably not. I've also forwarded the original docco > patch to Andrew Morton and LKML (which didn't receive them in first place). > completely my fault, I rolled them at the weekend whilst on a train, lived in effectively a Farraday cage for the weekend (a rural part of England for those who are curious :) and forgot....DOH! The patches are attached. If everyone likes the look of them, either one of you guys can 'signed off by' or I can to the mailing list. Cheers Alex > > Blaisorblade <[email protected]> [20050910 15:36:10 +0200]: > > > On Saturday 10 September 2005 14:59, Alexander Clouter wrote: > > > > Hi, > [About the flag behaviour] > > > > I'm all for this to be changed, its a feature that is ment to be for > > > > Joe Public to be used, it would be silly of us to not make it easier; > > > > it is confusing as it stands. > > > > Ok - hope there's no so much people workarounding for the new behaviour, > > > but they're smart enough to fix their scripts up. Just shout a bit on > > > LKML to say this and we should be ok. > > > My thinking too, its a relatively new feature and when I have looked around > > very few userland tools even tinker with ondemand so either we do it now or > > not at all...or rather we do it later and listen to everyone complain :) > > > > > Flipping the behaviour of the flag gets my vote. Do you want to roll > > > > the patch and I fix up the documentation or do you want to do both, or > > > > should do both? > > > > I think it's better that you do that - I'd already so many patches spread > > > in my trees that I'd lose this patch somewhere. > > > Not a problem. I'll roll them off right now. > > > Cheers > > -- > Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". > Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894) > http://www.user-mode-linux.org/~blaisorblade > > > > > > > ___________________________________ > Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB > http://mail.yahoo.it -- ______________________________________ / We have seen the light at the end of \ \ the tunnel, and it's out. / -------------------------------------- \ ^__^ \ (oo)\_______ (__)\ )\/\ ||----w | || ||
diff -u linux-2.6.13.orig/drivers/cpufreq/cpufreq_conservative.c linux-2.6.13/drivers/cpufreq/cpufreq_conservative.c
--- linux-2.6.13.orig/drivers/cpufreq/cpufreq_conservative.c 2005-09-23 15:24:46.605223250 +0100
+++ linux-2.6.13/drivers/cpufreq/cpufreq_conservative.c 2005-09-23 15:24:30.740231750 +0100
@@ -93,7 +93,7 @@
{
return kstat_cpu(cpu).cpustat.idle +
kstat_cpu(cpu).cpustat.iowait +
- ( !dbs_tuners_ins.ignore_nice ?
+ ( dbs_tuners_ins.ignore_nice ?
kstat_cpu(cpu).cpustat.nice :
0);
}
@@ -515,7 +515,7 @@
def_sampling_rate = (latency / 1000) *
DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
dbs_tuners_ins.sampling_rate = def_sampling_rate;
- dbs_tuners_ins.ignore_nice = 0;
+ dbs_tuners_ins.ignore_nice = 1;
dbs_tuners_ins.freq_step = 5;
dbs_timer_init();
diff -u linux-2.6.13.orig/drivers/cpufreq/cpufreq_ondemand.c linux-2.6.13/drivers/cpufreq/cpufreq_ondemand.c
--- linux-2.6.13.orig/drivers/cpufreq/cpufreq_ondemand.c 2005-09-23 15:24:46.609223500 +0100
+++ linux-2.6.13/drivers/cpufreq/cpufreq_ondemand.c 2005-09-23 15:24:08.846863500 +0100
@@ -86,7 +86,7 @@
{
return kstat_cpu(cpu).cpustat.idle +
kstat_cpu(cpu).cpustat.iowait +
- ( !dbs_tuners_ins.ignore_nice ?
+ ( dbs_tuners_ins.ignore_nice ?
kstat_cpu(cpu).cpustat.nice :
0);
}
@@ -424,7 +424,7 @@
def_sampling_rate = (latency / 1000) *
DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
dbs_tuners_ins.sampling_rate = def_sampling_rate;
- dbs_tuners_ins.ignore_nice = 0;
+ dbs_tuners_ins.ignore_nice = 1;
dbs_timer_init();
}
diff -r -u linux-2.6.13.orig/Documentation/cpu-freq/governors.txt linux-2.6.13/Documentation/cpu-freq/governors.txt --- linux-2.6.13.orig/Documentation/cpu-freq/governors.txt 2005-09-23 15:25:14.302954250 +0100 +++ linux-2.6.13/Documentation/cpu-freq/governors.txt 2005-09-23 15:36:09.875925000 +0100 @@ -27,6 +27,7 @@ 2.2 Powersave 2.3 Userspace 2.4 Ondemand +2.5 Conservative 3. The Governor Interface in the CPUfreq Core @@ -110,9 +111,64 @@ The CPUfreq govenor "ondemand" sets the CPU depending on the current usage. To do this the CPU must have the capability to -switch the frequency very fast. - +switch the frequency very quickly. There are a number of sysfs file +accessible parameters: +sampling_rate: measured in uS (10^-6 seconds), this is how often you +want the kernel to look at the CPU usage and to make decisions on +what to do about the frequency. Typically this is set to values of +around '10000' or more. + +show_sampling_rate_(min|max): the minimum and maximum sampling rates +available that you may set 'sampling_rate' to. + +up_threshold: defines what the average CPU usaged between the samplings +of 'sampling_rate' needs to be for the kernel to make a decision on +whether it should increase the frequency. For example when it is set +to its default value of '80' it means that between the checking +intervals the CPU needs to be on average more than 80% in use to then +decide that the CPU frequency needs to be increased. + +sampling_down_factor: this parameter controls the rate that the CPU +makes a decision on when to decrease the frequency. When set to its +default value of '5' it means that at 1/5 the sampling_rate the kernel +makes a decision to lower the frequency. Five "lower rate" decisions +have to be made in a row before the CPU frequency is actually lower. +If set to '1' then the frequency decreases as quickly as it increases, +if set to '2' it decreases at half the rate of the increase. + +ignore_nice: this parameter takes a value of '0' or '1', when set to +'0' then all processes are counted towards towards the 'cpu +utilisation' value. When set to '1' (its default) then processes that +are run with a 'nice' value will not count (and thus be ignored) in +the overal usage calculation. This is useful if you are running a CPU +intensive calculation on your laptop that you do not care how long it +takes to complete as you can 'nice' it and prevent it from taking part +in the deciding process of whether to increase your CPU frequency. + + +2.5 Conservative +---------------- + +The CPUfreq governor "conservative", much like the "ondemand" +governor, sets the CPU depending on the current usage. It differs in +behaviour in that it gracefully increases and decreases the CPU speed +rather than jumping to max speed the moment there is any load on the +CPU. This behaviour more suitable in a battery powered environment. +The governor is tweaked in the same manner as the "ondemand" governor +through sysfs with the addition of: + +freq_step: this describes what percentage steps the cpu freq should be +increased and decreased smoothly by. By default the cpu frequency will +increase in 5% chunks of your maximum cpu frequency. You can change this +value to anywhere between 0 and 100 where '0' will effectively lock your +CPU at a speed regardless of its load whilst '100' will, in theory, make +it behave identically to the "ondemand" governor. + +down_threshold: same as the 'up_threshold' found for the "ondemand" +governor but for the opposite direction. For example when set to its +default value of '20' it means that if the CPU usage needs to be below +20% between samples to have the frequency decreased. 3. The Governor Interface in the CPUfreq Core =============================================
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