Hi,

On 27/09/13 16:23, Graham Whaley wrote:
> I wish to work with you to remedy some of the listed issues. I've
> started working with MIPS hardware vendors on availability and pricing
> of hardware.

I've wondered if SMP Loongson systems are anywhere to be found:
http://bbs.lemote.com/viewthread.php?tid=43118

or if even the Lemote Hongri would be available someday:
http://www.lemote.com/products/computer/hongri/

But I don't see Loongson 3A being an option until at the very least
jessie kernels support it and are stable with all cores in use.  This is
just my opinion though and I can't speak for DSA.

> 3) speed. I see 'mips' (but not mipsel in particular) listed as 'too
> slow'. Sure, Can somebody point me at some indication of the minimum
> requirement here (not that I'm particularly aiming at the minimum, I
> just wish to ensure we reach it :-). And, is this just pure
> single-multi-core/thread-machine speed, or is it a solvable problem by
> using multiple machines if necessary ?

On mipsel at least, I recall that libreoffice, openjdk-7, webkit seemed
to have some difficulty building.  Each source package is built on a
single machine only, and the current machines are limited to <= 1 GiB
RAM I think so I expect heavy swapping takes place.

I speculated some time ago (in a mail to the DSA list) that
network-attached storage might help for low-powered buildds, but I
didn't do any followup viability testing of this yet.  I thought that a
separate NAS (of any architecture) would have no particular limit on
number of disks or RAM, should provide fault tolerance, and maybe help
with provisioning too.  Whereas current mipsel hardware may be limited
to a single disk, perhaps not adequately cooled or designed for
continuous running, without RAID or hot-swap, and either low in capacity
or very slow (due to I/O latency) than could be achieved even over a
100Mbps link to dedicated storage hardware.

During the wheezy freeze period, mipsel and others did develop large
queues of (IIRC >~150) packages in Needs-Build state.  That's something
that having more (and reliable) buildds could help with even if the same
spec as the existing ones.

> 4) I see there is a note about an 'opcode implementation error' for a
> mipsel porter box. Sounds like a new machine(s) is needed there as well.
> Could somebody point me at some data on the opcode issue (more out of
> interest really...).

I suspect that might refer to this, quoting from OpenBSD[0] :

> Unfortunately, most of the Loongson 2F-based hardware available at that
> time suffers from serious problems in the processor's branch prediction
> logic, causing the system to freeze, for which errata information only
> exists in the Chinese documentation (chapter 15, missing from the
> English translation), the only English language information being an
> e-mail[1] on a toolchain mailing-list.

[0]: http://www.openbsd.org/loongson.html
[1]: https://sourceware.org/ml/binutils/2009-11/msg00387.html

> From the three types of machines I see you currently have I believe
> there are more modern versions of all of those, and possibly some
> others. I believe we will be able to locate hardware to solve the issues.

I think Linux 3.2 detects and works around those bugs at least in kernel
code, but looking at the output in dmesg may help to identify which
boxes (if any) are affected.  (I imagine it's a problem for userland
binaries that were built before workarounds were added in binutils).

Maybe the existing boxes were not affected, but it was a concern about
acquiring newer Loongson 2F hardware?

Regards,
-- 
Steven Chamberlain
ste...@pyro.eu.org


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