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Date:      Mon, 24 Apr 2000 18:15:48 +0930
From:      Greg Lehey <grog@lemis.com>
To:        Lanny Baron <lnb@freedomtc.com>
Cc:        questions@FreeBSD.ORG, Lanny Baron <lnb@cybertouch.org>
Subject:   Re: SMP & RAID
Message-ID:  <20000424181548.E12676@freebie.lemis.com>
In-Reply-To: <XFMail.000424024626.lnb@freebsdsystems.com>
References:  <20000424120119.A12676@freebie.lemis.com> <XFMail.000424024626.lnb@freebsdsystems.com>

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On Monday, 24 April 2000 at  2:46:26 -0400, Lanny Baron wrote:
> On 24-Apr-00 Greg Lehey wrote:
>> On Sunday, 23 April 2000 at  2:27:42 -0400, Lanny Baron wrote:
>>> Hello,
>>> Can I get some information with respect to SNP and how well FreeBSD can
>>> handle up to 8 processors.
>>
>> You mean SMP (symmetrical multiprocessing)?  It depends on what you
>> want to do.  The big limitation is the giant kernel lock which only
>> allows one processor to run in kernel mode at any one time.  Depending
>> on your application, this may make no difference at all, or it may
>> completely bog it down.
>>
>>> Would anyone know what RAID cards are supported.
>>
>> Take a look at the release notes, for example
>> http://www.freebsd.org/releases/4.0R/notes.html.
>>
>>> Someone sent me mail saying that only Vinum will work.
>>
>> Don't rely on "someone".
>
> Yes sorry it is SMP. Typo.
> As for what type of application might require multiple cpu's, I
> would think large database applications. 

We've done some comparisons with Solaris in this area recently.  They
show that we have a long way to go to catch up with Solaris, and we're
planning to do some work on it.  At the moment, I wouldn't recommend
FreeBSD SMP for database applications.

> I know for a fact that a certain company with very large database
> bogs the entire network down for them. They run AIX and have several
> AS400's. A question then arises as to the claims of company's that
> sell systems and offer up to 8 CPU's. If FreeBSD cannot utilize the
> processing power, how can Linux?

As a followup to the Mindcraft benchmarks, Linux has given more
attention to kernel locking than we have.  Don't count on them being
behind us.

> This Kernel lock you speak of, is there anyway around it?

Sure, it's a SMOP (Simple Matter Of Programming).  It took Sun about 5
years to get where they are now.  Don't expect us to be any better.

Greg
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