Phoronix benchmarks DF 3.2 vs Ubuntu - question
Tomas Bodzar
tomas.bodzar at gmail.com
Wed Nov 28 11:36:14 PST 2012
On Wed, Nov 28, 2012 at 7:05 PM, Matthew Dillon
<dillon at apollo.backplane.com> wrote:
> In the past we've found that many of these so-called benchmarks
> are so poorly written that they don't actually test what they say they
> are testing.
This is excellent write up about such things
http://dtrace.org/blogs/brendan/2012/10/23/active-benchmarking/
> For example, quite a few of them wind up doing malloc()
> calls in critical loops, or gettimeofday(), or other unnecessary
> system calls, and stupid things like that. And as Alex said,
> a large chunk of any cpu benchmark that isn't written directly in
> assembly is going to test the compiler more than it will test the
> operating system.
>
> Similarly, file I/O benchmarks often focus on only reading or only
> writing and don't reflect the reality of mixed loads that most real-world
> systems have to contend with.
>
> Network benchmarks often test single-threaded or single-stream
> performance, which is pretty much worthless, far more than they
> test concurrent stream performance and fairness which servers are
> more likely to have to deal with.
>
> Benchmarks sometimes can identify bottlenecks and other issues that are
> worthy of action. The recent postgres/pgbench tests identified some
> significant issues that we were able to address in the release, for
> example.
>
> I glanced at that posting a week or three ago and generally speaking
> the more recent DragonFly did do marginally better, probably due to
> the positive effects the scheduler changes have on the cpu caches.
>
>
> -Matt
> Matthew Dillon
> <dillon at backplane.com>
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