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SubjectRe: [PATCH] flush icache before set_pte take6. [4/4] optimization for cpus other than montecito
On Mon, 30 Jul 2007 22:15:50 -0600
"David Mosberger-Tang" <dmosberger@gmail.com> 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.

I'm not sure this can happen before Montecito because L1 was write-through
and L2 was mixed.

> Or you really want to debug this *again* come next CPU?

No.
I should add RFC to this patch. I just want to hear opinions.
This is why I separated this patch. I can drop this.

Thanks,
-Kame






> --david
>
> On 7/30/07, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> >
> > Add "L2 cache is separated? check flag" as read_mostly global variable.
> >
> > This add one memory reference to global variable to page faults of "executable"
> > map in do_wp_page(page copy case), file-mapped page fault and some system calls
> > which does memory map changes. But not so bad as calling sync_icache_dcache in
> > architectures which doesn't need it.
> >
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> >
> >
> > ---
> > arch/ia64/kernel/setup.c | 7 +++++++
> > include/asm-ia64/pgtable.h | 3 ++-
> > 2 files changed, 9 insertions(+), 1 deletion(-)
> >
> > Index: linux-2.6.23-rc1.test/arch/ia64/kernel/setup.c
> > ===================================================================
> > --- linux-2.6.23-rc1.test.orig/arch/ia64/kernel/setup.c
> > +++ linux-2.6.23-rc1.test/arch/ia64/kernel/setup.c
> > @@ -106,6 +106,8 @@ struct io_space io_space[MAX_IO_SPACES];
> > EXPORT_SYMBOL(io_space);
> > unsigned int num_io_spaces;
> >
> > +int separated_l2_icache_dcache __read_mostly;
> > +
> > /*
> > * "flush_icache_range()" needs to know what processor dependent stride size to use
> > * when it makes i-cache(s) coherent with d-caches.
> > @@ -718,6 +720,11 @@ get_model_name(__u8 family, __u8 model)
> > printk(KERN_ERR
> > "%s: Table overflow. Some processor model information will be missing\n",
> > __FUNCTION__);
> > + /* Montecito has separated L2 Icache and Dcache. This requires
> > + synchronize Icache and Dcache before set_pte() */
> > + if (family == 0x20)
> > + separated_l2_icache_dcache = 1;
> > +
> > return "Unknown";
> > }
> >
> > Index: linux-2.6.23-rc1.test/include/asm-ia64/pgtable.h
> > ===================================================================
> > --- linux-2.6.23-rc1.test.orig/include/asm-ia64/pgtable.h
> > +++ linux-2.6.23-rc1.test/include/asm-ia64/pgtable.h
> > @@ -489,9 +489,10 @@ extern struct page *zero_page_memmap_ptr
> > * as an executable pte.
> > */
> > extern void __sync_icache_dcache(pte_t pte);
> > +extern int separated_l2_icache_dcache;
> > static inline void sync_icache_dcache(pte_t pte)
> > {
> > - if (pte_exec(pte))
> > + if (pte_exec(pte) && separated_l2_icache_dcache)
> > __sync_icache_dcache(pte);
> > }
> > #define __HAVE_ARCH_SYNC_ICACHE_DCACHE
> >
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-ia64" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> >
>
>
> --
> Mosberger Consulting LLC, http://www.mosberger-consulting.com/
>

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