Date: Wed, 2 May 2007 15:07:33 -0400 From: Kris Kennaway <kris@obsecurity.org> To: "Mars G. Miro" <marsgmiro@gmail.com> Cc: freebsd-stable@freebsd.org Subject: Re: mfs and buildworlds on da SunFire x4600 Message-ID: <20070502190732.GA42282@xor.obsecurity.org> In-Reply-To: <28edec3c0705021139h45c785c2s915941c0afb93b5d@mail.gmail.com> References: <28edec3c0705021139h45c785c2s915941c0afb93b5d@mail.gmail.com>
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On Thu, May 03, 2007 at 02:39:55AM +0800, Mars G. Miro wrote: > Greetz, > > I got my hands on a SunFire x4600. This is a dual-core 8-way > Opteron (dmesg shows 16 CPUs) w/c has 32G RAM. FreeBSD 6.2/amd64 runs > fine on it despite: > - 'reboot' doesnt work, machine just hangs in there. There is a sysctl to specify an alternate reboot method. > - front USB ports wont work for a USB keyboard, just use da ports at da > back. > > I've read a lot of threads in da past (and da BSDCan 2006 paper) > regarding mfs on /usr/src and /usr/obj to speed up buildworlds, > unfortunately it doesnt seem to improve things. I've tried both a > malloc and swap based async non-softupdates mfs (and rebooted da box > every after) but my buildworld speeds seem to be just da same as I do > it on da MPT SAS disk w/c is just around ~18mins. It is probably a combination of issues: 1) There is still some disk access because of accessing things like binaries in /usr. This will hurt more for parallel builds because your disk hardware is single-threaded, so I/O delays will serialize you. If you really wanted you could compare to a build in a md-hosted chroot to completely eliminate the disk, but this is just a game. 2) Buildworld doesn't parallelize well to 16 CPUs. Large parts of it are completely non-parallel. This is probably your main problem. You definitely should be measuring some difference - you need to use time(1) though instead of just estimating. Kris
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