----- Original Message ----- > From: "Greg KH" <[email protected]> > To: "CAI Qian" <[email protected]> > Cc: [email protected], "Andre Przywara" <[email protected]>, "H. Peter > Anvin" <[email protected]> > Sent: Friday, December 7, 2012 4:21:25 AM > Subject: Re: [PATCH 3.0.x] x86, amd: Disable way access filter on Piledriver > CPUs > > 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 :( Sorry, Greg. It looks like something going wrong from my side. I'll investigate and resubmit if necessary. Thanks for pointing out.
CAI Qian > > 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 > -- 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
