Alexey Kovyrin's Blog

Yet Another Admin's Blog

32bit VS 64bit – what do you use?

Posted by Alexey Kovyrin under Admin-tips, Development, General

Hello my dear readers.

Today I have a question for all of you. What platforms (32bit or 64 bit) do you use for your servers with more than 4Gb RAM? I’m asking because recently we‘ve hit few really weird bugs in Linux kernels 2.6.18 to 2.6.22 and all those bugs were PAE-related. Now I’d really love to move all machines to 64-bit, but I’m in doubt because we don’t know too much about Rails stack (ruby, mongrel, haproxy) on 64-bit platforms (all our DB boxes are 64-bit of course).

So, please drop me a line if you have any experience (negative or positive) with Rails platform on 64-bit machines. I’d really appreciate your help.

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11 Responses to this entry

cencio says:

we are using Win64, but mainly because there is M$ BI stack. Works good for us.

linux and PAE? why do not use lin64?

Scoundrel says:

2cencio: Actually there were many rumors regarding stability of ruby and mongrel on x86_64 boxes, but all stuff I’ve tried worked well so now I’m looking for more real-life examples from other people to make a final decision of switching our multi-million pageviews/day application entirely to 64-bit.

cencio says:

are you wanna make final decision after analyzing posts in Internet? not sure that it is good idea. Just try prototype x64 with 1-4 servers, test stability/performance and will have an answer

Scoundrel says:

2cencio: Actually to start testing this platform I wanted to make sure at least a few large rails users would report that it works :-) Now I have enough information (EngineYard and few other large rails users have 64bit stuff and it obviously works well) and we’re going to deploy our next app server on 64bit Ubuntu.

Anyways, thanks to all who answered.

Vasya Pupkin says:

Я ипосльзую amd64 ядро, но 32bit userspace.
В частности linux-image-2.6-amd64 но сама система 32bit, и никаких проблем с PAE. Понятно, что каждый отдельный процесс не сможет съесть в такой схеме более 2GB памяти.

Ram says:

Hey,

Any updates on the 32-bit versus 64-bit. Do you see any memory / performance degradation with the 64 bit? I have 8GB RAM and I am deciding if I should go with 64 bit or downgrade to 4GB RAM and get a 32 bit OS.

Thanks.

majek says:

We had the same problem [1]. Finally we chose 32 bits, because we could fit much more worker processes on a single host.

In our case we had python processes. On 64 bits one process used about 95MB RAM, on 32 bits about 60MB (there are a lot of pointers inside python).

So, by downgrading to 32 bits we could fit 30% more requests on one machine. And our next bottleneck became CPU rather than RAM.

We also wondered if 32 bits (with 8GB RAM) are slower than 64 bits. But some home made benchmarks showed that the performance degradation isn’t a problem (the results showed that 32 bits are 3-5% slower).

We tested also some combinations like 64 bits kernel and 32 bit userspace, but finally chose 32kernel/32userspace.

And what you finally chose and why?

[1] http://popcnt.org/2008/01/32-or-64-bits.html

anna says:

I am trying to download Flash so that i can watch videos on YouTube…but the website keeps telling me that i need a 32 bit to run it. My laptop is a 64 bit, so I am really frustrated because i cant get it to work.
HELP!