Hi Simon, wei.guo.si...@gmail.com writes: > From: Simon Guo <wei.guo.si...@gmail.com> > > This patch add VMX primitives to do memcmp() in case the compare size > exceeds 4K bytes. KSM feature can benefit from this.
You say "exceeds 4K" here. > diff --git a/arch/powerpc/lib/memcmp_64.S b/arch/powerpc/lib/memcmp_64.S > index f20e883..6303bbf 100644 > --- a/arch/powerpc/lib/memcmp_64.S > +++ b/arch/powerpc/lib/memcmp_64.S > @@ -27,12 +27,73 @@ > #define LH lhbrx > #define LW lwbrx > #define LD ldbrx > +#define LVS lvsr > +#define VPERM(_VRT,_VRA,_VRB,_VRC) \ > + vperm _VRT,_VRB,_VRA,_VRC > #else > #define LH lhzx > #define LW lwzx > #define LD ldx > +#define LVS lvsl > +#define VPERM(_VRT,_VRA,_VRB,_VRC) \ > + vperm _VRT,_VRA,_VRB,_VRC > #endif > > +#define VMX_OPS_THRES 4096 THRES == 4096 BTW, can we call it VMX_THRESH ? > +#define ENTER_VMX_OPS \ > + mflr r0; \ > + std r3,-STACKFRAMESIZE+STK_REG(R31)(r1); \ > + std r4,-STACKFRAMESIZE+STK_REG(R30)(r1); \ > + std r5,-STACKFRAMESIZE+STK_REG(R29)(r1); \ > + std r0,16(r1); \ > + stdu r1,-STACKFRAMESIZE(r1); \ > + bl enter_vmx_ops; \ > + cmpwi cr1,r3,0; \ > + ld r0,STACKFRAMESIZE+16(r1); \ > + ld r3,STK_REG(R31)(r1); \ > + ld r4,STK_REG(R30)(r1); \ > + ld r5,STK_REG(R29)(r1); \ > + addi r1,r1,STACKFRAMESIZE; \ > + mtlr r0 > + > +#define EXIT_VMX_OPS \ > + mflr r0; \ > + std r3,-STACKFRAMESIZE+STK_REG(R31)(r1); \ > + std r4,-STACKFRAMESIZE+STK_REG(R30)(r1); \ > + std r5,-STACKFRAMESIZE+STK_REG(R29)(r1); \ > + std r0,16(r1); \ > + stdu r1,-STACKFRAMESIZE(r1); \ > + bl exit_vmx_ops; \ > + ld r0,STACKFRAMESIZE+16(r1); \ > + ld r3,STK_REG(R31)(r1); \ > + ld r4,STK_REG(R30)(r1); \ > + ld r5,STK_REG(R29)(r1); \ > + addi r1,r1,STACKFRAMESIZE; \ > + mtlr r0 > + > +/* > + * LD_VSR_CROSS16B load the 2nd 16 bytes for _vaddr which is unaligned with > + * 16 bytes boundary and permute the result with the 1st 16 bytes. > + > + * | y y y y y y y y y y y y y 0 1 2 | 3 4 5 6 7 8 9 a b c d e f z z z | > + * ^ ^ ^ > + * 0xbbbb10 0xbbbb20 > 0xbbb30 > + * ^ > + * _vaddr > + * > + * > + * _vmask is the mask generated by LVS > + * _v1st_qw is the 1st aligned QW of current addr which is already loaded. > + * for example: 0xyyyyyyyyyyyyy012 for big endian > + * _v2nd_qw is the 2nd aligned QW of cur _vaddr to be loaded. > + * for example: 0x3456789abcdefzzz for big endian > + * The permute result is saved in _v_res. > + * for example: 0x0123456789abcdef for big endian. > + */ > +#define LD_VSR_CROSS16B(_vaddr,_vmask,_v1st_qw,_v2nd_qw,_v_res) \ > + lvx _v2nd_qw,_vaddr,off16; \ > + VPERM(_v_res,_v1st_qw,_v2nd_qw,_vmask) > + > /* > * There are 2 categories for memcmp: > * 1) src/dst has the same offset to the 8 bytes boundary. The handlers > @@ -174,6 +235,13 @@ _GLOBAL(memcmp) > blr > > .Llong: > +#ifdef CONFIG_ALTIVEC > + /* Try to use vmx loop if length is larger than 4K */ > + cmpldi cr6,r5,VMX_OPS_THRES > + bge cr6,.Lsameoffset_vmx_cmp Here we compare the length to 4K and if it's greater *or equal* then we go to the VMX case. Or am I reading it backward? So we should say "if the size is 4K or more we do VMX" shouldn't we? cheers
