Date: Fri, 11 Oct 2019 14:53:26 -0700 From: Brian Buhrow <buhrow@nfbcal.org> To: freebsd-xen@freebsd.org Subject: Re: i/o is very slow on FreeBSD dom0 with Xen-4.12 and Freebsd-12 Message-ID: <201910112153.x9BLrQSI028763@lothlorien.nfbcal.org> In-Reply-To: <201910102323.x9ANNACe003999@lothlorien.nfbcal.org>
next in thread | previous in thread | raw e-mail | index | archive | help
hello. Another data point on this issue. It appears the problem may be with the onboard IDE controllers, or, possibly, the way interrupts are handled. If I switch the BIOS to enable ahcisata mode instead of IDE mode for the SATA controllers, things boot more quickly, but the FreeBSD kernel is unable to talk to the hard drives. The ahci channels time out and we get stuck in an endless loop of CAM system retries. When the BIOS is set to Enhanced IDE mode, the FreeBSD kernel can talk to the drives, but the data rate is so slow as to be unusable. When FreeBSD boots on bare metal it can talk to the ahci or IDE drives without a problem. This makes me think Xen is messing with the interrupt handling of the IDE controller somehow. Is it possible the BIOS sets things up in a way that FreeBSD likes, but Xen does not? Perhaps the ioapic is programmed in a way that FreeBSD doesn't like? -thanks -Brian
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201910112153.x9BLrQSI028763>