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Date: Fri, 11 Aug 2006 11:06:00 -0700
From: "Jack Vogel" <jfvogel@gmail.com>
To: "Landon Fuller" <landonf@opendarwin.org>
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References: <20060811100536.V80282@k2.vol.cz>
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Cc: Daniel Ryslink <daniel.ryslink@col.cz>, freebsd-net@freebsd.org
Subject: Re: Problems with em interfaces on FreeBSD 6.1
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On 8/11/06, Landon Fuller <landonf@opendarwin.org> wrote:
>
> We saw this issue here on SMP systems running 6.1; I've been meaning
> to set up a reproduction case in the lab and dig into the issue further.
> Disabling the mpsafe network stack (debug.mpsafenet=0) is our
> temporary work-around; rwatson mentioned that this has the effect of
> forcing the interrupt handler for if_em to not run in parallel with
> the transmit code, which is likely what caused the problem to disappear.

Hmmm, I have code running right now that is required for new hardware, but
I think will benefit all, that only has the hardware writeback and interrupt on
the EOP descriptor. As it is now we have every descriptor written back.
I havent had it put thru extensive tests yet, but I expect it to significantly
reduce interrupts.

I hope to be submitting this stuff together with TSO support to CURRENT
soon, stay tuned.

Jack
Intel LAD