From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Date: Mon, 04 Apr 2005 07:09:57 +0000 Subject: Re: [PATCH] ULI 2.6.12 Message-Id: <20050404070957.GA4548@infradead.org> List-Id: References: <20050401130602.A123752@goliath.americas.sgi.com> In-Reply-To: <20050401130602.A123752@goliath.americas.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Mon, Apr 04, 2005 at 10:22:37AM +1000, Peter Chubb wrote: > However, I think that the thing that bothers me *most* about SGI's ULI > approach is that a full context switch is not done. The ULI runs as > if it were in the interrupted process's context. `current' isn't > changed, so it runs with the privileges of the interrupted process. > The *way* it runs (CPU bound, presumably) will affect the scheduler's > decisions about how to run the interrupted process in the next > timeslice. For most interrupt handlers this won't matter, but it'd be > relatively easy to construct a malicious one to slow particular > processes. I agree. Raymonds version looks like a hack for a very narrow special case to me. I really prefer your more portable and useful version, and I don't think the performance differences matter given today hardware.