Re: [patch] latency tracer, 2.6.15-rc7

From: Lee Revell
Date: Thu Dec 29 2005 - 15:19:59 EST


On Thu, 2005-12-29 at 15:11 -0500, Lee Revell wrote:
> On Thu, 2005-12-29 at 11:17 +0100, Ingo Molnar wrote:
> > * Dave Jones <davej@xxxxxxxxxx> wrote:
> >
> > > > could test it by e.g. trying to reproduce the same VM latency as in the
> > > > -rt tree. [the two zlib patches are needed if you are using 4K stacks,
> > > > mcount increases stack footprint.]
> > >
> > > kernel/latency.c: In function 'add_preempt_count_ti':
> > > kernel/latency.c:1703: warning: implicit declaration of function 'preempt_count_ti'
> > > kernel/latency.c:1703: error: invalid lvalue in assignment
> > > kernel/latency.c: In function 'sub_preempt_count_ti':
> > > kernel/latency.c:1764: error: invalid lvalue in assignment
> >
> > indeed - i have fixed this and have uploaded a new version to:
> >
> > http://redhat.com/~mingo/latency-tracing-patches/
>
> Still does not quite work for me on i386. I applied all the patches as
> I'm using 4K stacks.
>
> LD .tmp_vmlinux1
> init/built-in.o: In function `start_kernel':
> : undefined reference to `preempt_max_latency'
> make: *** [.tmp_vmlinux1] Error 1
>

This patch fixes the problem.

Lee

--- linux-2.6.15-rc5-rt2/kernel/latency.c~ 2005-12-29 14:04:26.000000000 -0500
+++ linux-2.6.15-rc5-rt2/kernel/latency.c 2005-12-29 15:23:32.000000000 -0500
@@ -71,9 +71,9 @@
* we clear it after bootup.
*/
#ifdef CONFIG_LATENCY_HIST
-static cycles_t preempt_max_latency = (cycles_t)0UL;
+cycles_t preempt_max_latency = (cycles_t)0UL;
#else
-static cycles_t preempt_max_latency = (cycles_t)ULONG_MAX;
+cycles_t preempt_max_latency = (cycles_t)ULONG_MAX;
#endif

static cycles_t preempt_thresh;


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