> From: Andy Lutomirski [mailto:l...@amacapital.net] > On 05/26/2014 10:01 AM, Fenghua Yu wrote: > > From: Fenghua Yu <fenghua...@intel.com> > > > > With ever growing extended state registers (xstate) on x86 processors, > kernel > > needs to cope with issue of growing memory space occupied by xstate. > The xsave > > area is holding more and more xstate registers, growing from legacy > FP and > > SSE to AVX, AVX2, AVX-512, MPX, and Intel PT. > > > > The recently introduced compacted format of xsave area saves xstates > only > > for enabled states. This patch set saves the xsave area space per > process > > in compacted format by xsaves/xrstors instructions. > > Are we going to want to encourage userspace to do something like > sticking vzeroupper right before each syscall to make any > xsaves/xrestores faster?
This patch set allow compacted format in kernel and standard format in user space. This works fine for both kernel and user application. As said in the patch 9/15, there would be two issues for user applications to use xsaves/xrstors: one is modified optimization doesn't work for user applications and the other one is legacy applications don't know compacted format of xsave area. So I don't see we need xsaves/xrstors in user space. But I could be wrong. Thanks. -Fenghua -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
