Messages in this thread Patch in this message | | | Date | Thu, 17 Feb 2005 05:01:39 -0800 | From | Frank Rowand <> | Subject | Re: [PATCH] Realtime preempt support for PPC |
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Ingo Molnar wrote: > * Frank Rowand <frowand@mvista.com> wrote: > > >>I have attached a patch to add realtime support for PowerPC (32 bit >>only). [...] > > > two comments: > > - why is us_to_tb needed? It just seems to add alot of unnecessary > clutter to the patch, while it's not used anywhere.
Sorry, the usage of us_to_tb got dropped from the patch when I moved it from one of my development trees to another. It gets used in usecs_to_cycles(). The patch to add that is attached below.
Even with the usage of us_to_tb by usecs_to_cycles(), there is a lot of added clutter for what is accomplished. I considered a nasty hack to try to derive the proper value from other sources, but adding us_to_tb seemed a lot easier to understand.
This patch also adds the dreaded #ifdefs, so I suspect it will not be the correct implementation long term. I'm not sure if Manish's patch included the ARM implementation of usecs_to_cycles() - it is a third case in the #ifdef.
Performance instrumentation is also going to need mcount() and _mcount(), which is currently a work in progress.
> > - could you submit the drivers/net/ibm_emac/ibm_emac_core.c patch > upstream as well?
Yes, I will do that.
> > otherwise it looks pretty clean and straightforward. > > Ingo
Source: MontaVista Software, Inc. Signed-off-by: Frank Rowand <frowand@mvista.com>
Index: linux-2.6.10/kernel/latency.c =================================================================== --- linux-2.6.10.orig/kernel/latency.c +++ linux-2.6.10/kernel/latency.c @@ -192,7 +192,11 @@ static unsigned long notrace cycles_to_u
static cycles_t notrace usecs_to_cycles(unsigned long delta) { +#if defined CONFIG_X86 return (cycles_t) delta * (cycles_t) (cpu_khz/1000+1); +#elif defined(CONFIG_PPC) + return delta * us_to_tb; +#endif }
#ifdef CONFIG_LATENCY_TRACE
Thanks,
-Frank (off to vacation for a couple days) -- Frank Rowand <frank_rowand@mvista.com> MontaVista Software, Inc
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