Date: Thu, 17 Jan 2008 09:27:23 -0700 From: Scott Long <scottl@samsco.org> To: Vivek Khera <vivek@khera.org> Cc: FreeBSD Stable List <freebsd-stable@freebsd.org> Subject: Re: What current Dell Systems are supported/work Message-ID: <478F81EB.2070601@samsco.org> In-Reply-To: <1608FD4D-72C2-4C16-890A-6ABA8FB20E57@khera.org> References: <DB4DDB04-1ADE-4C36-A846-BB6B7C12EB1B@patmedia.net> <200801101109.38294.jhb@freebsd.org> <70AABDAF-1925-4DBE-88A2-976CFBC55C5E@khera.org> <200801151340.46771.jhb@freebsd.org> <1608FD4D-72C2-4C16-890A-6ABA8FB20E57@khera.org>
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Vivek Khera wrote: > > On Jan 15, 2008, at 1:40 PM, John Baldwin wrote: > >>> Where can one go to read up on what MSI is and how it helps us? >>> >>> Is enabling it just setting a sysctl? Does that have to be done in >>> loader.conf or can it happen later? >> >> loader.conf (though it is now default on in RELENG_6). >> >> hw.pci.msi_enable=1 >> hw.pci.msix_enable=1 > > > Thanks for the info. But can anyone point me to some documentation on > why MSI is good for me? > When implemented and used correctly in the hardware and driver, it a lower overhead interrupt mechanism. It also expands the number of interrupt vectors available, making interrupt sharing non-existent (for right now, at least). Thirdly, it vastly simplifies interrupt routing and makes a lot of problems with missing interrupts at the OS/driver level go away. Scott
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