"Joerg Roedel" <joerg.roedel@amd.com> writes:Vojtech had one test that tested time monotonicity over CPUs and it constantly failed until we added the CPUID on K8 C stepping. He can give details on the test. I suspect the reason was because the CPU reordered the RDTSCs so that a later RDTSC could return a value before an earlier one. This can happen because gettimeofday() is so fast that a tight loop calling it can fit more than one iteration into the CPU's reordering window. That is why newer kernels use RDTSCP if available which doesn't need to be intercepted and is synchronous. And since all AMD SVM systems have RDTSCP they are fine. On Intel Core2 without RDTSCP the CPUID can be still intercepted right now, but the real fix there is to readd FEATURE_SYNC_TSC for Core2 -- the RDTSC there is always monotonic per CPU and the patch that changed that (f3d73707a1e84f0687a05144b70b660441e999c7) was bogus and must be reverted. I didn't catch that in time unfortunately. -Andi -
| Greg Kroah-Hartman | [PATCH 004/196] Chinese: add translation of SubmittingPatches |
| David Chinner | Re: [RFD] BIO_RW_BARRIER - what it means for devices, filesystems, and dm/md. |
| Andrew Morton | -mm merge plans for 2.6.23 |
| Trent Piepho | Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code |
git: | |
| David Miller | Re: iptables very slow after commit784544739a25c30637397ace5489eeb6e15d7d49 |
| Jarek Poplawski | [PATCH] pkt_sched: Destroy gen estimators under rtnl_lock(). |
| Gerrit Renker | [PATCH 27/37] dccp: Integration of dynamic feature activation - part 2 (server side) |
| David Miller | [GIT]: Networking |
