Re: [Linux-ia64] page size > 16KB

From: Mario Smarduch <cms063_at_email.mot.com>
Date: 2003-03-13 06:51:16
David Mosberger wrote:

> >>>>> On Wed, 12 Mar 2003 09:49:41 -0800, Jesse Barnes <jbarnes@sgi.com> said:
>
>   Jesse> Really?  What sorts of benchmarks have you done that show
>   Jesse> large improvements?  I ask because I can think of a few that
>   Jesse> might benefit, but have yet to see real world improvements of
>   Jesse> any significance, so I'm curious.
>
> Anything that's hurt significantly by TLB pressure will gain
> signifcantly.  Even apps that stream through memory (e.g., STREAMS)
> can see significant gains.  Other advantages are more reproducible
> results (since you're effectively getting some page coloring for
> "free") and much larger user virtual address space.

Hi David,
    I'm very curious about your statement regarding reproducible
results - a desirable attribute for many applications in our case
soft real-time predictability. With the caches on Itanium2 being
highly associative, did you notice a dramatic change in reproducibility
as you did in TLB efficiency? This is assuming a  locked memory intensive
application or this was too long ago for you to remember :)

- Mario.

>
> However, the part that really surprised me is how little ordinary apps
> seem to suffer from the higher page-fault latency and increased
> internal fragmentation.  I don't recall the exact numbers, but even a
> kernel compile ran almost as fast with 64KB page size as with 16KB
> page size.
>
> If you know of a real-world application that suffers significantly
> from 64KB page size, I'd like to hear about it.
>
>         --david
>
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Received on Wed Mar 12 11:51:53 2003

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