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

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 31 Mar 2017, Wei Liu wrote:
> 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...

Yes, good suggestion.

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