SCHED_ULE should not be the default

[O. Hartmann]

On 12/18/11 03:37, Bruce Cran wrote:
> On 13/12/2011 09:00, Andrey Chernov wrote:
>> I observe ULE interactivity slowness even on single core machine
>> (Pentium 4) in very visible places, like 'ps ax' output stucks in the
>> middle by ~1 second. When I switch back to SHED_4BSD, all slowness is
>> gone. 
> 
> I'm also seeing problems with ULE on a dual-socket quad-core Xeon
> machine with 16 logical CPUs. If I run "tar xf somefile.tar" and "make
> -j16 buildworld" then logging into another console can take several
> seconds. Sometimes even the "Password:" prompt can take a couple of
> seconds to appear after typing my username.
> 

I reported ages ago several problems using SCHED_ULE on FreeBSD 8/9 when
doing heavy I/O, either disk or network bound (that time I realised the
problem on servers doing heavy disk I/O or net I/O). It was suspected
that X could be the problem, but we also have a Dell PowerEdge 1950III
running FreeBSD 8.2-STABLE (by next week 9.0-RC[2/3]/STABLE) without X,
but the same problems, but no so prominent as with X. The box has 8
cores, 4 cores per socket each and 16 GB RAM, SAS 6/iR controller and
two PCI-X attached Broacom NexTreme NICs, so the hardware shouldn't be
any kind of trouble.

But that time (over the past two years for now), the problem was
considered "a personal" problem. Bah!

By the beginning of next year my working group expects new hardware.
Since we use for Linux for scientific work (due to OpenCL and CUDA on
TESLA cards), I can't use the Blade system. The boxes I expect is one
Dell Precission T7500, 96 GB RAM, two sockets, two Westmere XEONs each
socket with a summary of 12 cores/24 threads. I'll start a dual OS
installation with FreeBSD 10 and the most recent Suse (since the
development is mostly done by my colleagues on Suse for the C2075 TESLA
board, I need Suse Linux).
I will then being capable of performing some benchmarks on both boxes on
the very same hardware. The other box will be my desk's box, a brand new
Sandy-Bridge E CPU (i7-3960X) with 32 GB RAM. I'm also inclined to
install a dual boot box (I rejected this up to now since I do not like
to install GRUB2 for having multiboot when using GPT on FreeBSD). The
box will run with FreeBSD 9 and an Ubuntu or Gentoo Linux, if. I'm
unsure in the question of Linux, but I tend to have Gentoo for compiling
everything myself.
On this box, I also can perform benchmarks with several setups.

I see forward getting some help and/or tips to proof the issues we
discussed here.

Oliver

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