From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Peter H. Koenig" Subject: Re: About IO-APIC - General question Date: Fri, 03 May 2002 18:27:51 +0200 Sender: linux-smp-owner@vger.kernel.org Message-ID: <3CD2BA87.D03FB34C@phys.uni-paderborn.de> References: <3CBBC3D6.1947D011@phys.uni-paderborn.de> <3CBC0F3D.3010806@tzi.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: List-Id: Content-Type: text/plain; charset="us-ascii" To: linux-smp Hello, Klaas, I would like to thank you for the data you provided. >From your first paragraph I take that there is the possibility of specifying which processor(s) handle(s) interrupts manually. Klaas Zweck wrote: > i made some test on a linux-smp machine(kernel 2.4.9). > i had one process just doing some calculation on prim numbers. > i locked this to cpu 1 and disabled all interrupts on cpu 1. > ( in fact i routed all to cpu 0 ) > then i started a make -j4 bzImage job in a remote > shell to produce file i/o and network interrupts. > i restricted all processes except the one doing the calculation > from cpu 1 and delivered all interrupts only to cpu 0. Is it neccessary specifying this for getting interrupt sharing working ? My interrupts statistics table shows that the interrrupts are handled by one CPU solely: $ cat /proc/interrupts CPU0 CPU1 0: 84363 0 IO-APIC-edge timer 1: 2 0 IO-APIC-edge keyboard 2: 0 0 XT-PIC cascade 8: 1 0 IO-APIC-edge rtc 11: 1661 0 IO-APIC-level eth0 14: 8741 0 IO-APIC-edge ide0 15: 2 0 IO-APIC-edge ide1 NMI: 0 0 LOC: 84283 84281 ERR: 0 MIS: 0 This differs somehow from the (old) IO-APIC documentation where in the case of SMP-boards the IRQ load is shared between the processors. This problem occurs on a Supermicro P4DC6 using an unreleased bios release (without that so far the APIC has not been recognized at all), the MPS specification set to version 1.1 in the bios using kernel 2.4.10, 2.4.17 and 2.4.18. As some of the applications we run are quite Network or IO-intensive, we would like to take advantage of the IRQ sharing. Any suggestions ? Pete -- Dipl.-Chem. Peter H. Koenig FB 6 - Theoretische Physik Tel.: +49 5251 60 2332 Universitaet Paderborn Fax: +49 5251 60 3435 Pohlweg 55 33098 Paderborn