Date: Fri, 30 Dec 2005 08:56:44 +1100 From: Michael Vince <mv@roq.com> To: freebsd-stable@freebsd.org Subject: Re: RELENG_6: Which scheduler for SMP? Message-ID: <43B45B9C.9030406@roq.com> In-Reply-To: <43B2F0A8.2030609@freebsd.org> References: <43B2F0A8.2030609@freebsd.org>
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Mark Ovens wrote: > I've never had any success with the ULE scheduler on my dual Athlon > box running RELENG_5; it was so unstable it made Windows 3.1 look > stable. In fact my current build, cvsup'd a couple of days ago, won't > even boot with ULE. > > From what I remember, ULE was intended to become the default scheduler > during the life of 5.0 but that hasn't happened. > > I've just cvsup'd the source for RELENG_6 and I'm surprised to find in > the GENERIC config file: > > #options SCHED_ULE # ULE scheduler > options SCHED_4BSD # 4BSD scheduler > > so it seems 4BSD is still the default scheduler. Is ULE _still_ > considered to be in development/experimental? Even the SMP config file > doesn't use ULE. > > Also in GENERIC: > > options PREEMPTION # Enable kernel thread preemption > > [....] > > options ADAPTIVE_GIANT # Giant mutex is adaptive. > > Yet in src/sys/conf/NOTES, ADAPTIVE_GIANT is listed under SMP Options > and PREEMPTION is listed under SMP Debugging Options which makes it > surprising that they are in the GENERIC config file. > > What I am trying to decide is whether there any point in making the > jump from a very stable RELENG_5 system to RELENG_6. AIUI the ULE > scheduler and it's associated options optimize the use of multiple > CPUs and by staying with 4BSD I'm not getting the best performance > from my system. > > Can anyone offer any advice on this please? > > The machine has dual Athlon MP2800s on a Asus A7M266-D mobo, 1Gbyte > ECC RAM and all SCSI disks and optical drives. > > I have been benchmarking a Java servlet under ULE, and I couldn't get result scores as high under ULE as I could under the regular the 4BSD (although it wasn't far off) and when I left the machine benchmarking all night under ULE I came back in the morning to find the machine unresponsive and in need of a hard reboot. Mike
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