Mailinglist Archive: opensuse (389 mails)

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Re: [opensuse] Transparent Huge Pages
  • From: Per Jessen <per@xxxxxxxxxxxx>
  • Date: Wed, 20 Mar 2019 08:22:42 +0100
  • Message-id: <q6spo2$uvh$>
Dave Howorth wrote:

On Tue, 19 Mar 2019 20:08:57 +0100
Per Jessen <per@xxxxxxxxxxxx> wrote:

Dave Howorth wrote:

On Tue, 19 Mar 2019 20:15:37 +0300
Andrei Borzenkov <arvidjaar@xxxxxxxxx> wrote:

19.03.2019 16:20, Dave Howorth пишет:

I don't understand why madvise isn't the most useful.

Because then THP stops being Transparent.

But given the difficulties redis and php and presumably other
programs appear to have, the whole idea of transparency is a bug
not a feature, is it not?

Not if every system that doesn't run redis is doing better because of
it ?

There are a *lot* of systems that run PHP.

Sure, we have quite a few, but php is just a scripting language. The
vast majority of php apps will run with zero impact whether thp is on
or off.

And I'm sure there are lots of other applications that use small
memory blocks. Why should they be penalised?

IMO, that is not the general case - a few might suffer when running at
high load, that's all.

Surely it's better to have a design where programs that want to use
a new feature ask for it and programs that don't aren't forced to
use it?

huge pages is not really a user/application level feature.

what's madvise about then?

It's only advising the memory manager about intended sizes and patterns
of memory access. Whether or not that leads to huge pages is up to the
memory manager and in no way visible to the application.

Per Jessen, Zürich (1.4°C) - virtual servers, made in Switzerland.

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