Date: Sun, 17 Jun 2001 12:40:56 -0400 From: "Pedro F. Giffuni" <pfg1+@pitt.edu> To: freebsd-chat@FreeBSD.ORG Cc: Dag-Erling Smorgrav <des@ofug.org> Subject: Re: Article Network performance by OS Message-ID: <3B2CDD98.95548872@pitt.edu> References: <Pine.LNX.4.21.0106162345400.2056-100000@imladris.rielhome.conectiva> <xzpithv8xn8.fsf@flood.ping.uio.no>
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Dag-Erling Smorgrav wrote:
>
> Rik van Riel <riel@conectiva.com.br> writes:
> > Not quite. Linux distributions tend to be extremely
> > conservative in the IDE options (DMA, interrupt unmasking,
> > write caching, etc. all disabled) while FreeBSD seems to
> > have write caching and DMA on by default...
>
> Ahem.
>
> First of all, Linux' file system (ext2fs) is more or less equivalent,
> in terms of performance and integrity, to async ffs. This gives Linux
> a big performance edge out of the box, and FreeBSD a big reliability
> edge - but benchmark authors rarely care about fs integrity, as
> shutting off the power during heavy disk I/O isn't generally part of
> their benchmark.
>
This procedure would provide an excellent test of reliability. I
think, however, that it's easier to find and maintain an UPS instead
of hiring a FreeBSD expert. OK...tunning is not rocket science, but if
your want reliable operation you really need an UPS anyways, and
FreeBSD admins are not easily found (wrt to lusers and wusers).
> Second, we tried turning write caching on ATA drives off by default,
> and boy were you (the user community) pissed. Yes, turning wc off
> shows you just how crappy those non-tagged-queueing 4000 RPM ATA
> drives you picked up at Fry's for some pocket change are. So we
> turned it back on. If you're not happy with that, put 'hw.ata.wc="0"'
> in your /boot/loader.conf and they'll be off after the next reboot.
> Or get real disks.
>
Whatever the technical merits of turning wc off, I think it was a huge
mistake; especially since softupdates were not enabled by default.
People who (like me) buy those cheap, low quality, drives, are
actually expecting this "crappy" behaviour, but really appreciate
having a little more performance.
cheers,
Pedro.
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