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

[Punit Agrawal <punit.agrawal@xxxxxxx>]

Wei Liu <wei.liu2@xxxxxxxxxx> writes:

> 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.

Sure, I'll update it in the next version.

Thanks for your comments.

Punit

>
> This would avoid people asking question whether the check should be
> inverted...
>
> Wei.
>
>> Thanks,
>> Punit
>> 
>> >
>> >
>> > Wei.

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