Re: [Xen-devel] [For Xen-4.10 RFC PATCH 3/3] Prevent redundant icache flushes in populate_physmap()

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Fri, Mar 31, 2017 at 02:53:55PM +0100, Punit Agrawal wrote:
[...]
> 
> Correct!
> 
> invalidate_icache() flushes the entire instruction cache which ends up
> being called each time flush_page_to_ram() is invoked from
> alloc_heap_pages(). The patch prevents repeated calls to
> invalidate_icache() and moves the responsibility to populate_physmap()
> which was the intention.
> 
> It would help if you can explain why you think the changes are
> wrong.
> 

OK. So it turns out I misunderstood what you wanted to do here.

You can do this in a less confusing way. You don't need to fiddle with
a->memflags. Just add '| MEMF_no_icache_flush' to alloc_domheap_page.
And then you always call invalidate_icache at the end.

This would avoid people asking question whether the check should be
inverted...

Wei.

> Thanks,
> Punit
> 
> >
> >
> > Wei.

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