x86/fpu: Finish excising 'eagerfpu'

[karo-tx-linux.git] / arch / x86 / include / asm / fpu / types.h

diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index 48df486b02f9170e9ba6f9cb2b78f45eb3e53d4b..3c80f5b9c09d8cf5407378a39ba27cfa380bafbf 100644 (file)
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -321,17 +321,6 @@ struct fpu {
         */
        unsigned char                   fpregs_active;
 
-       /*
-        * @counter:
-        *
-        * This counter contains the number of consecutive context switches
-        * during which the FPU stays used. If this is over a threshold, the
-        * lazy FPU restore logic becomes eager, to save the trap overhead.
-        * This is an unsigned char so that after 256 iterations the counter
-        * wraps and the context switch behavior turns lazy again; this is to
-        * deal with bursty apps that only use the FPU for a short time:
-        */
-       unsigned char                   counter;
        /*
         * @state:
         *
@@ -340,29 +329,6 @@ struct fpu {
         * the registers in the FPU are more recent than this state
         * copy. If the task context-switches away then they get
         * saved here and represent the FPU state.
-        *
-        * After context switches there may be a (short) time period
-        * during which the in-FPU hardware registers are unchanged
-        * and still perfectly match this state, if the tasks
-        * scheduled afterwards are not using the FPU.
-        *
-        * This is the 'lazy restore' window of optimization, which
-        * we track though 'fpu_fpregs_owner_ctx' and 'fpu->last_cpu'.
-        *
-        * We detect whether a subsequent task uses the FPU via setting
-        * CR0::TS to 1, which causes any FPU use to raise a #NM fault.
-        *
-        * During this window, if the task gets scheduled again, we
-        * might be able to skip having to do a restore from this
-        * memory buffer to the hardware registers - at the cost of
-        * incurring the overhead of #NM fault traps.
-        *
-        * Note that on modern CPUs that support the XSAVEOPT (or other
-        * optimized XSAVE instructions), we don't use #NM traps anymore,
-        * as the hardware can track whether FPU registers need saving
-        * or not. On such CPUs we activate the non-lazy ('eagerfpu')
-        * logic, which unconditionally saves/restores all FPU state
-        * across context switches. (if FPU state exists.)
         */
        union fpregs_state              state;
        /*