Bug#406767: linux-image-2.6-3-amd64: rdtsc instruction does not serialise on core2 cpu's
Package: linux-image-2.6-3-amd64
Severity: critical
Justification: breaks the whole system
Commit from 2.6.18.6 upstream is vitally important for Core 2 family.
Without this TSC drift between cores will result in unpredictable
hard locks and reboots.
commit e4a835d383dc58212a9648ef905cb8087e0c4ab2
Author: Arjan van de Ven <arjan@linux.intel.com>
Date: Mon Dec 11 21:45:01 2006 +0100
[PATCH] x86-64: Mark rdtsc as sync only for netburst, not for core2
On the Core2 cpus, the rdtsc instruction is not serializing (as defined
in the architecture reference since rdtsc exists) and due to the deep
speculation of these cores, it's possible that you can observe time go
backwards between cores due to this speculation. Since the kernel
already deals with this with the SYNC_RDTSC flag, the solution is
simple, only assume that the instruction is serializing on family 15...
The price one pays for this is a slightly slower gettimeofday (by a
dozen or two cycles), but that increase is quite small to pay for a
really-going-forward tsc counter.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
[chrisw: backported to 2.6.18]
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
-- System Information:
Debian Release: 4.0
APT prefers unstable
APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)
Shell: /bin/sh linked to /bin/bash
Kernel: Linux 2.6.19.2
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Reply to: