Messages in this thread | | | Subject | Re: [PATCH v4 0/10] x86/xsaves: Fix XSAVES known issues | From | Dave Hansen <> | Date | Fri, 29 Apr 2016 13:03:43 -0700 |
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On 04/29/2016 12:57 PM, Yu-cheng Yu wrote: > On Fri, Apr 29, 2016 at 11:09:23AM -0700, Dave Hansen wrote: >> Once we *HAVE* XSAVES support, it also opens up the possibilities for >> doing things like dynamic XSAVE buffer allocation. For instance, let >> threads that are not _using_ AVX-512 not waste the 2k of space for >> it. > > If we can somehow modify exec* system call to scan the executable > binary (in user space) and pass along a bitmask containing xfeatures > used in the binary, and XSAVES is enabled in the kernel, we can > easily save a lot of memory. The kernel only needs to allocate space > for tasks that actually use xstates; most of them do not.
That's not feasible. Think of dynamic libraries or just-in-time compilers. What instruction set does /usr/bin/java use, for instance? :)
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