Date: Sun, 17 Jun 2001 07:24:23 -0500 From: Mike Meyer <mwm@mired.org> To: Rik van Riel <riel@conectiva.com.br> Cc: freebsd-chat@FreeBSD.ORG, freebsd-hackers@FreeBSD.ORG Subject: Re: Article Network performance by OS Message-ID: <15148.41335.928818.113165@guru.mired.org> In-Reply-To: <Pine.LNX.4.21.0106162345400.2056-100000@imladris.rielhome.conectiva> References: <006701c0f6b9$dd6d89e0$3fac6395@alink> <Pine.LNX.4.21.0106162345400.2056-100000@imladris.rielhome.conectiva>
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Rik van Riel <riel@conectiva.com.br> types:
> On Sat, 16 Jun 2001, Jonathan Fortin wrote:
> > Linux is tuned out of the box, where the others are tuned for
> > stability.
> 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...
This doesn't agree with what was said about IDE write cache in Linux
when it was toggled in FBSD. At that point, it was claimed that 1)
Linux left the disk write cache in whatever state it found it in, and
2) most drives shipped with write cache enabled, just so they would
peform well on benchmarks. In other words - it's generally on by
default.
On the other hand, all those other options can make a *lot* of
difference. I've got some old tests I ran on 3.x wd driver with a
brand new disk. Here's what bonnie says for one test with none of the
go-fast options on:
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
wd 100 2300 14.2 2285 6.7 1350 6.0 2499 17.7 2729 6.5 123.4 3.2
And here's what it says when you turn on UDMA and all those good things:
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
wd 100 16841 88.5 15186 26.1 16610 38.2 21409 100.0 133543 100.0 3004.7 48.6
<mike
P.S. - no, I'm not presenting this as if it were a real benchmark. I
just happened to have these numbers laying around as part of some
other work I did. But the change is impressive.
--
Mike Meyer <mwm@mired.org> http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.
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