Date: Wed, 23 Nov 2005 03:46:53 -0500 From: Kris Kennaway <kris@obsecurity.org> To: John Polstra <jdp@polstra.com> Cc: net@freebsd.org, current@freebsd.org, Kris Kennaway <kris@obsecurity.org> Subject: Re: em interrupt storm Message-ID: <20051123084653.GA90927@xor.obsecurity.org> In-Reply-To: <XFMail.20051122205449.jdp@polstra.com> References: <20051123030304.GA84202@xor.obsecurity.org> <XFMail.20051122205449.jdp@polstra.com>
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--jRHKVT23PllUwdXP Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Nov 22, 2005 at 08:54:49PM -0800, John Polstra wrote: >=20 > On 23-Nov-2005 Kris Kennaway wrote: > > I am seeing the em driver undergoing an interrupt storm whenever the > > amr driver receives interrupts. In this case I was running newfs on > > the amr array and em0 was not in use: > >=20 > > 28 root 1 -68 -187 0K 8K CPU1 1 0:32 53.98% irq16= : em0 > > 36 root 1 -64 -183 0K 8K RUN 1 0:37 27.75% irq24= : amr0 > >=20 > ># vmstat -i > > interrupt total rate > > irq1: atkbd0 2 0 > > irq4: sio0 199 1 > > irq6: fdc0 32 0 > > irq13: npx0 1 0 > > irq14: ata0 47 0 > > irq15: ata1 931 5 > > irq16: em0 6321801 37187 > > irq24: amr0 28023 164 > > cpu0: timer 337533 1985 > > cpu1: timer 337285 1984 > > Total 7025854 41328 > >=20 > > When newfs finished (i.e. amr was idle), em0 stopped storming. > >=20 > > MPTable: <INTEL SE7520BD22 > >=20 > This is the dreaded interrupt aliasing problem that several of us have > experienced with this chipset. High-numbered interrupts alias down to > interrupts in the range 16..19 (or maybe 16..23), a multiple of 8 less > than the original interupt. >=20 > Nobody knows what causes it, and nobody knows how to fix it. This would be good to document somewhere so that people don't either accidentally buy this hardware, or know what to expect when they run it. Kris --jRHKVT23PllUwdXP Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (FreeBSD) iD8DBQFDhCx8Wry0BWjoQKURAoSZAJ45iXxWGfFc7G8++HwAmr9wAD0OpgCfQp4t pDBtasCrA64KmsHmt8UqJ3M= =2hmE -----END PGP SIGNATURE----- --jRHKVT23PllUwdXP--
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