Hi there,
On 4/29/07, Peter A. H. Peterson <[EMAIL PROTECTED]> wrote:
Hi Everyone,
My name is Peter Peterson and I represent a group of a grad students
at UCLA. We're in a computer systems performance analysis course and we
were hoping to do a general performance comparison of gentoo vs. a
popular binary i386-compatible distribution (probably ubuntu) in some
"real-world" server tests to try and meaningfully calculate the
performance gains that local compilation provides. (For example,
apache2 requests processed per second on the same hardware.)
I've subscribed to this list because we want the gentoo community to
be involved in helping us design the tests so that we can hopefully
all feel good about what and how we are testing the systems.
We have no particular outcome in mind; our group represents a wide
range of computer users, from Mac, Linux, and Windows enthusiasts, and
we have all used a wide variety of Linux distributions. We have simply
noticed that much of the discussion of gentoo's performance advantage
is anecdotal and we're genuinely hoping to provide some meaningful
experimental data for discussion. Also, if anyone knows of any
available benchmark data or papers on this subject, we'd love to hear
about them. There was apparently a paper on slashdot a couple of years
ago, but the host it was on appears to now be squatted. For that
matter, if this is a well understood or closed issue (for example, if
the statistics that people quote are actually from good experimental
data) please let us know.
Is anyone here interested in discussing this project? We are
specifically interested in discussing methodology, testing suits,
CFLAGS and other options. Our desire is not to "trick out" gentoo or
ubuntu, but rather quantify the performance benefit that gentoo has
over binary distributions with "normal" compile flags (whatever normal
is).
A good CFLAGS would be something not very agressive, something like:
-march= -O3 or -O2 and at most -fomit-frame-pointer.
(Scientific workloads can speedup considerably with: -ffast-math)
Having experienced and done some benchmarks with gentoo and other
distros on servers and on scientific workstations.
What I found is that sometimes gentoo lacks critical performance
patches in glibc that are applied to mainstream distros (redhat,
suse..etc) that provide boosts in memcpy, memset, etc..(I remmember a
discussion about that some years ago).
What I also found out is that the compiler flags only affect
workloads that are very compute intensive. not something that depends
almost completely on FSB load or IO load.. like most server
workloads... -O3 doesn't do much to a working set full of
unpredictable branches (like server workloads usually are) and low IPC
rate.
I really do believe performance boost from gentoo to be practically
negligible. The difference will only be apreciable in very few corner
cases. Most distros also optimize critical aplications such has:
openssl, mplayer.. reducing the possible corner cases.
Anyways, doing a "academic" benchmark would be a good idea.
Something like:
micro-benchmarks:
- stream (mem bandwith benchmark)
- ??
macro-benchmarks:
- apache2 + gzip + php(make it cpu intensive, not IO intensive)
- xmlmark ?
- kernelbench
- pybench ?
- openssl bench
about methodology:
- same system, same bios version, same disks.
- All OSes must be installed in the same disk partitions.
- the will be trouble about the kernel config:
- for mainstream distros you should use the kernel that is provided.
- for gentoo, gentoo-sources configured by someone which is
experienced, and informed about configuration impacts on performance
(ideally a kernel hacker?).
- should use the stable versions in gentoo portage?
- or should use the same application versions used on mainstream distro?
--
Miguel Sousa Filipe
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