On Thu, Nov 25, 2010 at 7:38 AM, Vishwanath BS <vishwanath.bs@xxxxxx> wrote: > Currently cpufreq transition latency value does not really reflect the actual > OMAP OPP transition delay. This patch has the actual latency value. > I did profile the DVFS latency on OMAP3430, OMAP3630 and OMAP4 for worstcase(MPU and Core together) and found that in none of these platforms, transiton value > goes beyong 10ms. Added a buffer of 20ms to avoid too frequent ondemand timer > expiry. > With this change, performance of ondemand governor is improved when tested > using cpufreqbench tool. Without this patch, cpufreq-bench reported ondemand > performance as 40% of performance governor, and with this patch it's around 70% > (using below procedure). > > cpufreq-bench: > http://lwn.net/Articles/339862/ > http://ftp.riken.go.jp/archives/Linux/suse/people/ckornacker/cpufreq-bench/ > > Command used for performance testing: > cpufreq-bench -l 50000 -s 100000 -x 50000 -y 100000 -g ondemand -r 5 -n 5 -v > > Signed-off-by: Vishwanath BS <vishwanath.bs@xxxxxx> > --- > arch/arm/plat-omap/cpu-omap.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > mode change 100644 => 100755 arch/arm/plat-omap/cpu-omap.c > > diff --git a/arch/arm/plat-omap/cpu-omap.c b/arch/arm/plat-omap/cpu-omap.c > old mode 100644 > new mode 100755 > index c47faf8..d3fc423 > --- a/arch/arm/plat-omap/cpu-omap.c > +++ b/arch/arm/plat-omap/cpu-omap.c > @@ -158,8 +158,8 @@ static int __init omap_cpu_init(struct cpufreq_policy *policy) > policy->max = policy->cpuinfo.max_freq; > policy->cur = omap_getspeed(0); > > - /* FIXME: what's the actual transition time? */ > - policy->cpuinfo.transition_latency = 300 * 1000; > + /* Program the actual transition time for worstcase */ > + policy->cpuinfo.transition_latency = 30 * 1000; Vishwa, This is a frequent periodic timer. Does a smaller value have any affect on CPUidle wakeups? Thanks, Mike > return 0; > } > -- > 1.7.0.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-omap" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
