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Date: Wed, 17 Nov 2004 10:45:16 +0000 (GMT)
From: Robert Watson <rwatson@freebsd.org>
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To: Poul-Henning Kamp <phk@phk.freebsd.dk>
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Subject: Re: [HEADSDOWN]  I'm done for now.
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On Wed, 17 Nov 2004, Poul-Henning Kamp wrote:

> Giant is now pushed down through select/poll/ioctl. 
> 
> Please test and report problems. 

Great!  This should hopefully both reduce contention on Giant in
interesting cases (such as select-intensive socket stuff), as well as
reduce the overal number of locking operations for some interesting paths
(i.e., select on sockets, which previously paid the cost of
locking/unlocking Giant but didn't need it). 

FWIW, I would not be surprised if we see some bug reports come in now that
ioctl() is being run without Giant for the network stack back default.
While some of those ioctl's are already running without Giant due to
sharing code paths with set/getsockopt() and internal use of ioctl in the
kernel, others have probably not seen as much exposure.  Likewise, while
the pipe ioctl code should be MPSAFE (and is pretty innocuous), that's not
been confirmed.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Principal Research Scientist, McAfee Research