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Old 11-30-2009, 08:16 PM
Kurt Hansen
 
Default non-threaded perl no longer in .spec file

Hello,

I'm setting up a new server on 5.4 and noticed this in the perl.spec file:


* Mon Jul 21 2008 Stepan Kasal - 4:5.8.8-14.el5
- add two patches, which...
- Resolves: #435505, #431041
- remove %%define threading, the non-threading variant is not supported,
Related: 435376


That comment wasn't there when I set up a server on 5.2 a few months
back and the %define threading option was still in the perl.spec file,
making it easy for me to create my own non-threaded perl.

I want a non-threaded perl because the mod_perl folks say that the
performance is better on a non-threaded perl.

I believe I can compare the spec files and figure out where to edit the
new spec file, but I wondered about that "not supported" comment.

Is there something "bad" about the non-threading variant?

Thanks!

Take care,

Kurt Hansen
khansen@charityweb.net
_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 11-30-2009, 09:36 PM
Robert Heller
 
Default non-threaded perl no longer in .spec file

At Mon, 30 Nov 2009 16:16:43 -0500 CentOS mailing list <centos@centos.org> wrote:

>
> Hello,
>
> I'm setting up a new server on 5.4 and noticed this in the perl.spec file:
>
>
> * Mon Jul 21 2008 Stepan Kasal - 4:5.8.8-14.el5
> - add two patches, which...
> - Resolves: #435505, #431041
> - remove %%define threading, the non-threading variant is not supported,
> Related: 435376
>
>
> That comment wasn't there when I set up a server on 5.2 a few months
> back and the %define threading option was still in the perl.spec file,
> making it easy for me to create my own non-threaded perl.
>
> I want a non-threaded perl because the mod_perl folks say that the
> performance is better on a non-threaded perl.
>
> I believe I can compare the spec files and figure out where to edit the
> new spec file, but I wondered about that "not supported" comment.
>
> Is there something "bad" about the non-threading variant?

Probably the same thing that is bad about a single core processor.
Which are pretty much no longer available (except for processors meant
for little SBC/Embedded systems). I suspect that either RH or (more
likely) the Perl people don't want to have to support two versions of
Perl, one with and one without threading.

>
> Thanks!
>
> Take care,
>
> Kurt Hansen
> khansen@charityweb.net
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>
>

--
Robert Heller -- 978-544-6933
Deepwoods Software -- Download the Model Railroad System
http://www.deepsoft.com/ -- Binaries for Linux and MS-Windows
heller@deepsoft.com -- http://www.deepsoft.com/ModelRailroadSystem/

_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 11-30-2009, 09:47 PM
 
Default non-threaded perl no longer in .spec file

> At Mon, 30 Nov 2009 16:16:43 -0500 CentOS mailing list <centos@centos.org>
> wrote:
<snip>
>> Is there something "bad" about the non-threading variant?
>
> Probably the same thing that is bad about a single core processor.
> Which are pretty much no longer available (except for processors meant
> for little SBC/Embedded systems). I suspect that either RH or (more

I'll call you on that. A *lot* of people, both at home and in offices, are
running single core systems, and will be for years. Most folks can't
afford to upgrade every year or two... and since *most* folks are running
office software, browsing the Web, and doing email, don't *need* to.

Besides, this *is* Linux we're talking about, which runs on *everything*,
including 386's....

mark

_______________________________________________
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Old 11-30-2009, 10:02 PM
"nate"
 
Default non-threaded perl no longer in .spec file

Robert Heller wrote:

> Probably the same thing that is bad about a single core processor.
> Which are pretty much no longer available (except for processors meant
> for little SBC/Embedded systems). I suspect that either RH or (more
> likely) the Perl people don't want to have to support two versions of
> Perl, one with and one without threading.

Single core CPUs may be rare but single core VMs probably
represent the dominant number of deployments out there as it's much
more efficient scheduler wise to go with more single CPUs than fewer
multi CPU VMs.

Not that I have any problem running multithreaded apps on a single
CPU, I do it all the time. It is kind of unconventional using a
load balancer to spread load specifically for optimal hypervisor
scheduling though(traffic is load balanced regardless).

nate


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Old 11-30-2009, 10:26 PM
 
Default non-threaded perl no longer in .spec file

> Robert Heller wrote:
>
>> Probably the same thing that is bad about a single core processor.
>> Which are pretty much no longer available (except for processors meant
>> for little SBC/Embedded systems). I suspect that either RH or (more
>> likely) the Perl people don't want to have to support two versions of
>> Perl, one with and one without threading.
>
> Single core CPUs may be rare but single core VMs probably
> represent the dominant number of deployments out there as it's much
> more efficient scheduler wise to go with more single CPUs than fewer
> multi CPU VMs.
<snip>
Good point. In fact, where I was working earlier this year, they had
several long phone calls with VMware's support, who advised them
explicitly to allocate as few cores as possible, because one VM might wait
a *lot* longer if it was looking for 4 or 8 cores, while other VMs were
using several, whereas if it only wanted 2, or 1, it would get its time
slice a lot sooner.

mark

_______________________________________________
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http://lists.centos.org/mailman/listinfo/centos
 
Old 11-30-2009, 10:34 PM
Robert Heller
 
Default non-threaded perl no longer in .spec file

At Mon, 30 Nov 2009 15:47:24 -0700 (MST) CentOS mailing list <centos@centos.org> wrote:

>
> > At Mon, 30 Nov 2009 16:16:43 -0500 CentOS mailing list <centos@centos.org>
> > wrote:
> <snip>
> >> Is there something "bad" about the non-threading variant?
> >
> > Probably the same thing that is bad about a single core processor.
> > Which are pretty much no longer available (except for processors meant
> > for little SBC/Embedded systems). I suspect that either RH or (more
>
> I'll call you on that. A *lot* of people, both at home and in offices, are
> running single core systems, and will be for years. Most folks can't
> afford to upgrade every year or two... and since *most* folks are running
> office software, browsing the Web, and doing email, don't *need* to.

All I meant was it is hard to get a *new* single core processor. Yes,
there are lots of *old* single core systems that will continue in
service for years. I was going to get a single-core Semperon from
Newegg for my new system, but before I could raise the money to get
one, Newegg discontinued the only remaining AMD single core processor
they carried (all of the Intel ones are multi-core). I did find one
from a discount/closeout place with some in stock (and they had a
counter showing how many were left in stock).

>
> Besides, this *is* Linux we're talking about, which runs on *everything*,
> including 386's....

Sure, although most distros don't provide stock kernels for anything
less than a '586.

>
> mark
>
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>
>

--
Robert Heller -- 978-544-6933
Deepwoods Software -- Download the Model Railroad System
http://www.deepsoft.com/ -- Binaries for Linux and MS-Windows
heller@deepsoft.com -- http://www.deepsoft.com/ModelRailroadSystem/

_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 12-02-2009, 01:19 PM
Kurt Hansen
 
Default non-threaded perl no longer in .spec file

Robert Heller wrote:
> At Mon, 30 Nov 2009 16:16:43 -0500 CentOS mailing list <centos@centos.org> wrote:
>
>
>> Hello,
>>
>> I'm setting up a new server on 5.4 and noticed this in the perl.spec file:
>>
>> * Mon Jul 21 2008 Stepan Kasal - 4:5.8.8-14.el5
>> - add two patches, which...
>> - Resolves: #435505, #431041
>> - remove %%define threading, the non-threading variant is not supported,
>> Related: 435376
>>
>>
>> That comment wasn't there when I set up a server on 5.2 a few months
>> back and the %define threading option was still in the perl.spec file,
>> making it easy for me to create my own non-threaded perl.
>>
>> I want a non-threaded perl because the mod_perl folks say that the
>> performance is better on a non-threaded perl.
>>
>> I believe I can compare the spec files and figure out where to edit the
>> new spec file, but I wondered about that "not supported" comment.
>>
>> Is there something "bad" about the non-threading variant?
>>
>
> Probably the same thing that is bad about a single core processor.
> Which are pretty much no longer available (except for processors meant
> for little SBC/Embedded systems). I suspect that either RH or (more
> likely) the Perl people don't want to have to support two versions of
> Perl, one with and one without threading.
>
Actually, I'm pretty sure that this is a decision by RH alone. If
anything, the "Perl people" advised against it. Everything I've read by
perl developers is that threading is a performance hit in perl unless
you've written your program specifically to take advantage of threading.
Most perl programs don't, so it would be better for those who use perl
the most if the default version were the non-threaded one. However, I
realize that choosing the threaded version almost assuredly is preferred
by a majority of RH users. It has been clear by choices RH has made over
the years with respect to perl that heavy users of perl in Apache are
not a core constituency of RH. Those of us who do use perl extensively
on RH distributions have to adapt. I only wish RH made it easier.

I do know, though, that there is a set of perl modules, called bioperl,
used extensively by folks analyzing the human genome. Plus, they even
have a pretty large cluster at the National Institutes of Health running
on CentOS. I wonder if a lot of those modules are optimized for threaded
perl?

The program that I use the most, mod_perl, which is a persistent perl
interpreter in Apache, was not written to take advantage of threading.
The mod_perl developers report that you can get a 20-30% increase in
performance by using a non-threaded perl vs a threaded one.

No-one's brought up any problems with the non-threaded one, so I think
I'll go ahead with my own spec file and rebuilding perl.

Thank you!

Take care,

Kurt Hansen
khansen@charityweb.net
_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 

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