Date: Mon, 12 Jul 1999 10:06:14 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: Luoqi Chen <luoqi@watermarkgroup.com>, dfr@nlsystems.com, jeremyp@gsmx07.alcatel.com.au, freebsd-current@FreeBSD.ORG, mike@ducky.net Subject: Re: "objtrm" problem probably found (was Re: Stuck in "objtrm") Message-ID: <199907121706.KAA70338@apollo.backplane.com> References: <20136.931798322@critter.freebsd.dk>
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:> p.s. I'm pretty sure that the lock prefix costs nothing on a UP system,
:> and probably wouldn't be noticed on an SMP system either because the
:> write-allocation overhead is already pretty bad. But I haven't tested
:> it.
:
:it's actually quite expensive in terms of bus bandwidth because a lot of
:things have to be synchronized and stalled...
:
:--
:Poul-Henning Kamp FreeBSD coreteam member
:phk@FreeBSD.ORG "Real hackers run -current on their laptop."
:FreeBSD -- It will take a long time before progress goes too far!
It depends on which L1/L2 cache model Intel is using. I wouldn't expect
it to be much more expensive then a standard read-modify-write, but I
will run some tests on an SMP box between two user processes to get some
hard numbers.
-Matt
Matthew Dillon
<dillon@backplane.com>
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