Date: Thu, 24 Jun 1999 00:09:43 -0600 From: Wes Peters <wes@softweyr.com> To: Julian Elischer <julian@whistle.com> Cc: "Russell L. Carter" <rcarter@pinyon.org>, hackers@FreeBSD.ORG Subject: Re: Microsoft performance (was: ...) Message-ID: <3771CBA7.4973C681@softweyr.com> References: <Pine.BSF.3.95.990623213838.993R-100000@current1.whistle.com>
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Julian Elischer wrote:
>
> ok here are some of the problems..
>
> Matt's changes allow dd to copy data at 2.5 times the rate it did before.
> I consider dd to be an application. The problem is due to resource
> handling in the kernel and results in large amounts of Idle CPU time.
>
> Another primary problem with the FreeBSD kernel (being addressed by Kirk)
> is that after writing a file, once the data has been queued for IO you
> cannot read the data in that file (even though it is present) until the IO
> is complete. With 64 tags, it is concievable that this could take a half
> second on a modern disk.
>
> These are problems shown up by the benchmarks but
> which can be shown to affect ordinary operations.
>
> There are other problems related to SMP and the GKL..
> e.g.. two processes cannot access buffers at the same time, even though
> they are both present , because only one of them is allowed in the kernel
> at a time. Therefore One processor will spend a bunch of time at idle..
I think it's been pretty well known since the beginning that FreeBSD
SMP performance is nothing to cheer about. How does FreeBSD fare
against NT or other systems on single processor systems?
I think we call consider SMP to be a "work in progress."
--
"Where am I, and what am I doing in this handbasket?"
Wes Peters Softweyr LLC
http://www.softweyr.com/~softweyr wes@softweyr.com
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