Re: [PATCH v2 1/4] introduce zero filled pages handler

From: Konrad Rzeszutek Wilk
Date: Tue Mar 19 2013 - 12:44:27 EST

On Sat, Mar 16, 2013 at 2:24 PM, Dan Magenheimer
<dan.magenheimer@xxxxxxxxxx> wrote:
>> From: Konrad Rzeszutek Wilk [mailto:konrad@xxxxxxxxxx]
>> Subject: Re: [PATCH v2 1/4] introduce zero filled pages handler
>> > +
>> > + for (pos = 0; pos < PAGE_SIZE / sizeof(*page); pos++) {
>> > + if (page[pos])
>> > + return false;
>> Perhaps allocate a static page filled with zeros and just do memcmp?
> That seems like a bad idea. Why compare two different
> memory locations when comparing one memory location
> to a register will do?

Good point. I was hoping there was an fast memcmp that would
do fancy SSE registers. But it is memory against memory instead of

Perhaps a cunning trick would be to check (as a shortcircuit)
check against 'empty_zero_page' and if that check fails, then try
to do the check for each byte in the code?

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