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SubjectRe: [PATCH] add a clear_pages function to clear pages of higher order
>>>>> On Tue, 5 Apr 2005 17:15:53 -0700 (PDT), Christoph Lameter <clameter@engr.sgi.com> said:

Christoph> On Thu, 24 Mar 2005, David Mosberger wrote:
>> That's definitely the case. See my earlier post on this topic:

>> http://www.gelato.unsw.edu.au/linux-ia64/0409/11012.html

>> Unfortunately, nobody reported any results for larger machines
>> and/or more interesting workloads, so the patch is in limbo at
>> this time. Clearly, if the CPU that's clearing the page is
>> likely to use that same page soon after, it'd be useful to use
>> temporal stores.

Christoph> Here are some numbers using lmbench of temporal writes
Christoph> vs. non temporal writes on ia64 (8p machine but lmbench
Christoph> run only for one load). There seems to be some benefit
Christoph> for fork/exec but overall this does not seem to be a
Christoph> clear win. I suspect that the distinction between
Christoph> temporal vs. nontemporal writes is be more beneficial on
Christoph> machines with smaller pagesizes since the likelyhood that
Christoph> most cachelines of a page are used soon is increased and
Christoph> therefore hot zeroing is more beneficial.

What LMbench test other than fork/exec would you have expected to be
affected by this? LMbench is not a good benchmark for this (remember:
it's a _micro_ benchmark).

--david
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