Re: HEADSUP: MPSAFE network drivers
From: Sam Leffler (sam_at_errno.com)
Date: 10/30/03
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To: Pawel Jakub Dawidek <nick@garage.freebsd.pl> Date: Thu, 30 Oct 2003 08:01:23 -0800
On Thursday 30 October 2003 01:22 am, Pawel Jakub Dawidek wrote:
> On Wed, Oct 29, 2003 at 11:52:48AM -0700, Sam Leffler wrote:
> +> I'm committing changes to mark various network drivers' interrupt
> handlers +> MPSAFE. To insure folks have a way to backout if they hit
> problems I've also +> added a tunable that lets you disable this w/o
> rebuilding your kernel. By +> default all network drivers that register an
> interrupt handler INTR_MPSAFE +> are setup to run their ISR w/o Giant. If
> you want to defeat this w/o +> changing the code you can set
> +>
> +> debug.mpsafenet=0
> +>
> +> from the loader when booting and the MPSAFE bit will automatically be
> removed. +> I plan to use this to also control forthcoming changes for
> registering MPSAFE +> netisrs.
> +>
> +> The following drivers are marked MPSAFE:
> +>
> +> ath, em, ep, fxp, sn, wi, sis
> +>
> +> I've got changes coming for bge. Other drivers probably can be marked
> MPSAFE +> but I'm only doing it for those drivers that I can test.
>
> Because there is so many drivers, maybe you could prepare some regression
> tests designed to check changed things. This will allow people to test your
> changes - it is not very easy now if we don't know what we're looking for
> exactly PLUS those drivers aren't marked MPSAFE by default.
Unfortunately there is no easy way to decide if the locking in a driver is
correct; otherwise I'd simply test them and not provide a fallback as a I
did. Before I commit any driver I run with it for at least a few weeks (in
some cases months) on a variety of machines (workstation, server, laptop,
firewall). If there are no problems then I commit the change. The driver
changes I committed yesterday I've been running for >4 months. Likewise, the
next round of locking changes to push Giant up have been running for ~2
months.
Otherwise the main safeguard I use are numerous assertions to validate
assumptions.
Sam
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- Previous message: Jan.Stary_at_ff.cuni.cz: "'/etc/rc.d/pccard restart' starts a second one"
- In reply to: Pawel Jakub Dawidek: "Re: HEADSUP: MPSAFE network drivers"
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