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From: Punit Agrawal <punit.agrawal@arm.com>
To: Wei Liu <wei.liu2@citrix.com>
Cc: sstabellini@kernel.org, George.Dunlap@eu.citrix.com,
	andrew.cooper3@citrix.com, tim@xen.org, xen-devel@lists.xen.org,
	julien.grall@arm.com, jbeulich@suse.com,
	ian.jackson@eu.citrix.com
Subject: Re: [For Xen-4.10 RFC PATCH 3/3] Prevent redundant icache flushes in populate_physmap()
Date: Fri, 31 Mar 2017 15:27:18 +0100	[thread overview]
Message-ID: <87tw69bjy1.fsf@e105922-lin.cambridge.arm.com> (raw)
In-Reply-To: <20170331141050.cmxep46xghqcdss3@citrix.com> (Wei Liu's message of "Fri, 31 Mar 2017 15:10:50 +0100")

Wei Liu <wei.liu2@citrix.com> 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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  reply	other threads:[~2017-03-31 14:27 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-31 10:24 [For Xen-4.10 RFC PATCH 0/3] Reduce unnecessary icache maintenance operations Punit Agrawal
2017-03-31 10:24 ` [For Xen-4.10 RFC PATCH 1/3] Allow control of icache invalidations when calling flush_page_to_ram() Punit Agrawal
2017-03-31 23:53   ` Stefano Stabellini
2017-03-31 10:24 ` [For Xen-4.10 RFC PATCH 2/3] arm: p2m: Prevent redundant icache flushes Punit Agrawal
2017-03-31 23:54   ` Stefano Stabellini
2017-04-03 10:45     ` Punit Agrawal
2017-03-31 10:24 ` [For Xen-4.10 RFC PATCH 3/3] Prevent redundant icache flushes in populate_physmap() Punit Agrawal
2017-03-31 11:34   ` Wei Liu
2017-03-31 13:53     ` Punit Agrawal
2017-03-31 14:10       ` Wei Liu
2017-03-31 14:27         ` Punit Agrawal [this message]
2017-03-31 23:58         ` Stefano Stabellini
2017-05-09 15:16   ` Julien Grall
2017-05-12 12:35     ` Punit Agrawal

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