On Wed, 2007-10-31 at 17:57 +0800, Zhang, Yanmin wrote: > On Tue, 2007-10-30 at 16:36 +0800, Zhang, Yanmin wrote: > > On Tue, 2007-10-30 at 08:26 +0100, Ingo Molnar wrote: > > > * Zhang, Yanmin <[EMAIL PROTECTED]> wrote: > > > > > > > sub-bisecting captured patch > > > > 38ad464d410dadceda1563f36bdb0be7fe4c8938(sched: uniform tunings) > > > > caused 20% regression of aim7. > > > > > > > > The last 10% should be also related to sched parameters, such like > > > > sysctl_sched_min_granularity. > > > > > > ah, interesting. Since you have CONFIG_SCHED_DEBUG enabled, could you > > > please try to figure out what the best value for > > > /proc/sys/kernel_sched_latency, /proc/sys/kernel_sched_nr_latency and > > > /proc/sys/kernel_sched_min_granularity is? > > > > > > there's a tuning constraint for kernel_sched_nr_latency: > > > > > > - kernel_sched_nr_latency should always be set to > > > kernel_sched_latency/kernel_sched_min_granularity. (it's not a free > > > tunable) > > > > > > i suspect a good approach would be to double the value of > > > kernel_sched_latency and kernel_sched_nr_latency in each tuning > > > iteration, while keeping kernel_sched_min_granularity unchanged. That > > > will excercise the tuning values of the 2.6.23 kernel as well. > > I followed your idea to test 2.6.24-rc1. The improvement is slow. > > When sched_nr_latency=2560 and sched_latency_ns=640000000, the performance > > is still about 15% less than 2.6.23. > > I got the aim7 30% regression on my new upgraded stoakley machine. I found > this mahcine is slower than the old one. Maybe BIOS has issues, or > memeory(Might not > be dual-channel?) is slow. So I retested it on the old machine and found on > the old > stoakley machine, the regression is about 6%, quite similiar to the > regression on tigerton > machine. > > By sched_nr_latency=640 and sched_latency_ns=640000000 on the old stoakley > machine, > the regression becomes about 2%. Other latency has more regression. > > On my tulsa machine, by sched_nr_latency=640 and sched_latency_ns=640000000, > the regression becomes less than 1% (The original regression is about 20%). > > When I ran a bad script to change the values of sched_nr_latency and > sched_latency_ns, > I hit OOPS on my tulsa machine. Below is the log. It looks like > sched_nr_latency becomes > 0.
Oops, yeah I think I overlooked that case :-/
I think limiting the sysctl parameters make most sense, as a 0 value
really doesn't.
Signed-off-by: Peter Zijlstra <[EMAIL PROTECTED]>
---
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 3b4efbe..0f34c91 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -94,6 +94,7 @@ static int two = 2;
static int zero;
static int one_hundred = 100;
+static int int_max = INT_MAX;
/* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
static int maxolduid = 65535;
@@ -239,7 +240,10 @@ static struct ctl_table kern_table[] = {
.data = &sysctl_sched_nr_latency,
.maxlen = sizeof(unsigned int),
.mode = 0644,
- .proc_handler = &proc_dointvec,
+ .proc_handler = &proc_dointvec_minmax,
+ .strategy = &sysctl_intvec,
+ .extra1 = &one,
+ .extra2 = &int_max,
},
{
.ctl_name = CTL_UNNUMBERED,
signature.asc
Description: This is a digitally signed message part
