Date: Sun, 8 Jun 2014 11:48:08 -0700 From: Kevin Oberman <rkoberman@gmail.com> To: George Mitchell <george+freebsd@m5p.com> Cc: FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org> Subject: Re: Not to beat a dead horse, but ... Message-ID: <CAN6yY1vQ2TL3Gf=jfcJ7DeSH3dBQ41pomiFWBqHa=W3KdjutiQ@mail.gmail.com> In-Reply-To: <5394A848.7030609@m5p.com> References: <5394A848.7030609@m5p.com>
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On Sun, Jun 8, 2014 at 11:15 AM, George Mitchell <george+freebsd@m5p.com> wrote: > When I run this command on 10-STABLE on a uniprocessor system while > running the misc/dnetc port: > > cd /usr/src > time make buildworld && time make buildkernel && time make installkernel > > On revision 266422 with SCHED_ULE, I get (showing the time lines only): > > 7045.988u 897.681s 4:00:33.89 55.0% 29430+492k 27927+17003io > 30943pf+519w > 1155.683u 149.422s 52:49.60 41.1% 25418+410k 7452+20843io > 12166pf+248w > 7.101u 4.838s 8:03.57 2.4% 5905+221k 1179+9461io 1345pf+67w > > On revision 267211 with SCHED_4BSD: > > 6950.087u 665.074s 2:40:36.19 79.0% 29929+502k 33651+17368io > 31151pf+151w > 1148.066u 134.312s 26:40.95 80.1% 26234+426k 9681+24613io > 11917pf+106w > 6.774u 4.369s 0:33.90 32.8% 3110+320k 1388+10979io 1514pf+3w > > Since the majority of my systems are uniprocessors and I like to > run dnetc, SCHED_ULE has been a dealbreaker for me since day one. > Consequently I can't use freebsd_update. > > The party line seems to be, "Well, everybody knows SCHED_ULE sucks > on uniprocessors." Hello? Not everybody has upgraded to multiple > core or hyperthreaded processors yet. Do we really want to write > off every uniprocessor piece of hardware out here? > > The other assertion I hear is that SCHED_ULE really excels on some > unspecified workload or other. I'd love to see exactly how much > better it does than 4BSD on these mythological loads. -- George > I am also at least ambivalent about the merits of ULE. The choice to run 4BSD does not prevent the use of freebsd_update. It does require a kernel re-build after the update, though. Just keep a GENERIC kernel (which can be downloaded for any release) in /boot. freebsd-update will use that for the upgrade. Once the upgrade is complete you can build the kernel as you wish, and reboot. Just leave /boot/GENERIC there to have it ready for the next time you need to upgrade or update. There is no need to rebuild the modules when all your custom kernel does is to switch schedulers, so it is fairly quick. This may not be adequate for you, but it does remove the need for many of the steps in the full system re-build. Full instructions for all of this are in Chapter 23, Section 2 of the Handbook. -- R. Kevin Oberman, Network Engineer, Retired E-mail: rkoberman@gmail.com
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