From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Mackerras Subject: Re: [patch 13/26] Xen-paravirt_ops: Consistently wrap paravirt ops callsites to make them patchable Date: Wed, 21 Mar 2007 11:03:14 +1100 Message-ID: <17920.30274.608018.34484@cargo.ozlabs.ibm.com> References: <20070316.023331.59468179.davem@davemloft.net> <45FB005D.9060809@goop.org> <1174127638.8897.75.camel@localhost.localdomain> <20070318.003309.71088169.davem@davemloft.net> <20070318120814.GA45869@muc.de> <1174272469.11680.23.camel@localhost.localdomain> <1174348905.11680.54.camel@localhost.localdomain> <45FF4043.4000805@vmware.com> <45FF770C.7050301@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: netdev-owner@vger.kernel.org To: Linus Torvalds Cc: Jeremy Fitzhardinge , Zachary Amsden , Rusty Russell , "Eric W. Biederman" , Andi Kleen , David Miller , mingo@elte.hu, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, virtualization@lists.osdl.org, xen-devel@lists.xensource.com, chrisw@sous-sol.org, anthony@codemonkey.ws, netdev@vger.kernel.org List-Id: virtualization@lists.linuxfoundation.org Linus Torvalds writes: > We should just do this natively. There's been several tests over the years > saying that it's much more efficient to do sti/cli as a simple store, and > handling the "oops, we got an interrupt while interrupts were disabled" as > a special case. > > I have this dim memory that ARM has done it that way for a long time > because it's so expensive to do a "real" cli/sti. > > And I think -rt does it for other reasons. It's just more flexible. 64-bit powerpc does this now as well. Paul.