On Fri, Nov 30, 2012 at 05:21:35AM -0500, CAI Qian wrote: > x86, amd: Disable way access filter on Piledriver CPUs > > The Way Access Filter in recent AMD CPUs may hurt the performance of > some workloads, caused by aliasing issues in the L1 cache. > This patch disables it on the affected CPUs. > > The issue is similar to that one of last year: > http://lkml.indiana.edu/hypermail/linux/kernel/1107.3/00041.html > This new patch does not replace the old one, we just need another > quirk for newer CPUs. > > The performance penalty without the patch depends on the > circumstances, but is a bit less than the last year's 3%. > > The workloads affected would be those that access code from the same > physical page under different virtual addresses, so different > processes using the same libraries with ASLR or multiple instances of > PIE-binaries. The code needs to be accessed simultaneously from both > cores of the same compute unit. > > More details can be found here: > http://developer.amd.com/Assets/SharedL1InstructionCacheonAMD15hCPU.pdf > > CPUs affected are anything with the core known as Piledriver. > That includes the new parts of the AMD A-Series (aka Trinity) and the > just released new CPUs of the FX-Series (aka Vishera). > The model numbering is a bit odd here: FX CPUs have model 2, > A-Series has model 10h, with possible extensions to 1Fh. Hence the > range of model ids. > > Signed-off-by: Andre Przywara <[email protected]> > Link: http://lkml.kernel.org/r/[email protected] > Signed-off-by: H. Peter Anvin <[email protected]> > > Upstream-ID: 2bbf0a1427c377350f001fbc6260995334739ad7 > Stable-trees: 3.0.x > Signed-off-by: CAI Qian <[email protected]>
This patch fails to build on the 3.0-stable kernel. Please, if you are going to submit patches for stable kernel trees, at least build-test properly :( greg k-h -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
