[erlang-questions] Fwd: Maximising memory compactness

Andreas Schumacher andreas@REDACTED
Fri Apr 4 17:26:01 CEST 2014

Honestly, we did not measure the number of users, but we made a rough guess
based on the questions, comments, and/or bug reports we got for the
half-word emulator.


-----Original Message-----
From: Tuncer Ayaz [mailto:tuncer.ayaz@REDACTED]
Sent: den 4 april 2014 14:25
To: Andreas Schumacher
Cc: erlang-questions@REDACTED; Olivier BOUDEVILLE
Subject: Re: [erlang-questions] Fwd: FW: Maximising memory compactness

On Fri, Apr 4, 2014 at 1:33 PM, Andreas Schumacher wrote:
> As a matter of fact, the half-word emulator will be deprecated in OTP
> 17.0, which will be released next week. The reason for that is that
> there have been very few (if any) users; and thus, the maintenance
> costs outweigh its value.

FWIW, I use it. But more importantly, how did you measure the number of
users? For comparison, JVM's compressed oops has been default enabled for a
long time, but to be precise it's not _exactly_ the same thing.

"Compressed oops is supported and enabled by default in Java SE 6u23 and
later. In Java SE 7, use of compressed oops is the default for 64-bit JVM
processes when -Xmx isn't specified and for values of -Xmx less than 32


That said, what about implementing x32 ABI support as an alternative?
As far as I can tell this would have to be explicitly implemented in HiPE

> -----Original Message-----
> From: erlang-questions-bounces@REDACTED
> [mailto:erlang-questions-bounces@REDACTED] On Behalf Of Kostis
> Sagonas
> Sent: den 4 april 2014 11:39
> To: Erlang
> Subject: Re: [erlang-questions] Maximising memory compactness
> On 04/04/2014 10:33 AM, Olivier BOUDEVILLE wrote:
>> Let's suppose one would like to run a large, distributed (Erlang)
>> application, with many processes, and that ends up, in some cases,
>> being RAM-bound.
>  > ...
>> The half-word emulator would seem the simplest/most elegant solution
>> to do so ....
>  >
>> So, my question: would relying on a set of 32-bit VMs per host,
>> instead of a single 64-bit VM, look like the best option here?
> My opinion is (and has always been) that the half-word emulator seems
> cute on the surface but deep down is a bad idea (esp. for a language
> with automatic memory management like Erlang, or if your application
> has any plans of growing someday).
> So I would really advice against it. In fact, IMO it's better to try
> to forget about its existence for anything other than for small
> embedded devices or in machines that do not have more than 3GB of
> memory.
> Unfortunately, I am very busy to elaborate more on this right now.
> But even if I had more time, I would probably try to find better
> things to do than think/talk about the half-word emulator. Leaning
> back and relax until you forget about it (or simply waiting for the
> day that it is taken out of the distribution) is preferable IMO.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://erlang.org/pipermail/erlang-questions/attachments/20140404/06d0818b/attachment.htm>

More information about the erlang-questions mailing list