Date: Mon, 2 Feb 2004 11:17:54 +1000 (EST) From: Andy Farkas <andyf@speednet.com.au> To: John Baldwin <jhb@freebsd.org> Cc: cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/i386/i386 apic_vector.s src/sys/i386/isa atpic_vector.s Message-ID: <20040202110437.N88162@hewey.af.speednet.com.au> In-Reply-To: <200401282044.i0SKi8Y6063747@repoman.freebsd.org> References: <200401282044.i0SKi8Y6063747@repoman.freebsd.org>
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On Wed, 28 Jan 2004, John Baldwin wrote: > Modified files: > sys/i386/i386 apic_vector.s > sys/i386/isa atpic_vector.s > Log: > Optimize the i386 interrupt entry code to not reload the segment registers > if they already contain the correct kernel selectors. What effect on performance does this change have? It seems to be a rather significant change to an important code path, or am I totally confused..? Also, you've changed: movl $KDSEL, %eax ; /* reload with kernel's data segment */ and, movl $KPSEL, %eax ; /* reload with per-CPU data segment */ to: mov $KDSEL,%ax ; /* load kernel ds, es and fs */ and, mov $KPSEL,%ax ; Is this part of the optimisations? Or, could you briefly explain this change? Thank you. -- :{ andyf@speednet.com.au Andy Farkas System Administrator Speednet Communications http://www.speednet.com.au/
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