linux-kernel - Re: [PATCH] flush icache before set_pte take6. [4/4] optimization for cpus other than montecito

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Date:	Tue, 31 Jul 2007 19:17:49 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Zoltan Menyhart <Zoltan.Menyhart@...l.net>
Cc:	David Mosberger-Tang <dmosberger@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-ia64@...r.kernel.org" <linux-ia64@...r.kernel.org>,
	"tony.luck@...el.com" <tony.luck@...el.com>,
	Christoph Lameter <clameter@....com>
Subject: Re: [PATCH] flush icache before set_pte take6. [4/4] optimization
 for cpus other than montecito

On Tue, 31 Jul 2007 10:38:48 +0200
Zoltan Menyhart <Zoltan.Menyhart@...l.net> wrote:

> David Mosberger-Tang wrote:
> > This seems crazy to me.  Flushing should occur according to the
> > *architecture*, not model-by-model.  Even if we happen to get "lucky"
> > on pre-Montecito CPUs, that doesn't justify such ugly hacks.  Or you
> > really want to debug this *again* come next CPU?
> > 
> >   --david
> 
> O.K. let's say we flush by default: the global flag is set.
> 
> We can have a (short) list of the CPU models which do not require
> this flush.
> 
> If all of the CPUs are on the list then clear the global flag. And:
> 
> static inline void sync_icache_dcache(pte_t pte) {
>        if (pte_exec(pte) && global_flag)
>                __sync_icache_dcache(pte);
> }
> 

Could we discuss this in other thread as "optimization for some cpus" and
push bug-fix patches first ?

If take5 or part of take6(patch 1,2) are not acceptable, I'll continue this
work on -rc2.

Thanks,
-Kame

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