Date: Sun, 18 Dec 2011 00:00:15 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: Adrian Chadd <adrian@FreeBSD.org> Cc: George Mitchell <george+freebsd@m5p.com>, freebsd-stable@FreeBSD.org, Oliver Pinter <oliver.pntr@gmail.com> Subject: Re: SCHED_ULE should not be the default Message-ID: <4EED10EF.1030108@FreeBSD.org> In-Reply-To: <CAJ-VmokoexQdgcWsW5ufGHCdQ-nzdPcjgYyftA52eSNGcurpfw@mail.gmail.com> References: <4EE1EAFE.3070408@m5p.com> <CAJ-FndDniGH8QoT=kUxOQ%2BzdVhWF0Z0NKLU0PGS-Gt=BK6noWw@mail.gmail.com> <4EE2AE64.9060802@m5p.com> <4EE88343.2050302@m5p.com> <CAFHbX1%2B5PttyZuNnYot8emTn_AWkABdJCvnpo5rcRxVXj0ypJA@mail.gmail.com> <4EE933C6.4020209@zedat.fu-berlin.de> <CAPjTQNEJDE17TLH-mDrG_-_Qa9R5N3mSeXSYYWtqz_DFidzYQw@mail.gmail.com> <4EECD261.2080208@m5p.com> <4EED05EC.8050103@FreeBSD.org> <CAJ-VmokoexQdgcWsW5ufGHCdQ-nzdPcjgYyftA52eSNGcurpfw@mail.gmail.com>
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on 17/12/2011 23:20 Adrian Chadd said the following: > Erm, just as a random question - since device drivers (and GEOM) run > as separate threads, has anyone looked into what kind of effects the > scheduler has on these? > > I definitely have measurable throughput/responsiveness differences > between ULE and 4BSD (and preempt/non-preempt on 4BSD) on my MIPS > boards when they're bridging traffic. I wonder if there's something > strange going on with the scheduling and preemption of driver netisrs, > taskqueues, the fast interrupt handlers, etc. > > This may -not- be a userland specific problem.. That's an interesting idea. From the recent discussion about USB I can conclude that USB threads run at higher priority than GEOM threads: PI_NET/PI_DISK vs PRIBIO. The former is from the ithread range, the latter is from the regular kernel range. Maybe it would make sense to give the GEOM threads a priority from the ithread range too - given their role and importance. -- Andriy Gapon
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