Re: [PATCH 6/6] sched: disabled rt-bandwidth by default

From: Ingo Molnar
Date: Thu Aug 28 2008 - 09:07:45 EST



* Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:

> There is no customer issue and there is no handwaving about
> compliance;

well, the reason i'm asking is that i cannot for anything in the world
imagine you being so upset about _anything_ but something that involves
benchmark runs ;-)

And what does SCHED_FIFO RT policy scheduling have to do with
performance and benchmarks? Nothing usually in the real world, except
for this little known fact: a common 'tuning' for TPC database
benchmarks is to run all DB threads as SCHED_FIFO to squeeze the last
0.1% of performance out of the setup.

So - and i'm taking an educated guess here - is SCHED_FIFO+TPC
performance perhaps one of the factors that played a role in you
initiating this thread? If yes then it's obviously an incredibly broken
use of SCHED_FIFO and we can add the sysctl tuning to the long list of
dozens of other tunings that happen before a TPC run anyway.

Hm?

Ingo
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