Re: [PATCH] drm/i915: Use hash tables for the command parser

["Volkin, Bradley D" <bradley.d.volkin@intel.com>]

On Thu, May 08, 2014 at 06:15:44AM -0700, Lespiau, Damien wrote:
> On Thu, May 08, 2014 at 02:05:07PM +0100, Damien Lespiau wrote:
> > On Mon, Apr 28, 2014 at 08:22:08AM -0700, bradley.d.volkin@intel.com wrote:
> > > From: Brad Volkin <bradley.d.volkin@intel.com>
> > > +/*
> > > + * Different command ranges have different numbers of bits for the opcode.
> > > + * In order to use the opcode bits, and only the opcode bits, for the hash key
> > > + * we should use the MI_* command opcode mask (since those commands use the
> > > + * fewest bits for the opcode.)
> > > + */
> > > +#define CMD_HASH_MASK STD_MI_OPCODE_MASK
> > 
> > This is not very convicing (but could well be correct).
> > 
> > #define STD_MI_OPCODE_MASK  0xFF800000
> > #define STD_3D_OPCODE_MASK  0xFFFF0000
> > 
> > So it only works if the 3D opcodes have the top 9 bits all distinct?
> 
> To expand on that, with the attached program:
> 
> $ ./minimal-hash-hsw-render  | wc -l
> 44
> 
> $ ./minimal-hash-hsw-render  | sort -u | wc -l
> 37

Yes, as it's currently written, some commands may hash to the same
bucket. The per-bucket search will use the full mask from the cmd
descriptor to get an exact match.

The issue is that, for example, MI commands in a batch may use bits
22:16 for something other than the opcode (e.g. GGTT vs PPGTT). If we
mask a command from a batch with 0xFFFF0000 then an MI command may hash
to the wrong bucket. If we want a perfect hash then I suppose we should
look at bits 31:29 and mask with the exact STD_xx_OPCODE_MASK for the
client. The existing INSTR_CLIENT_MASK/SHIFT defines could be reused
for that.

Brad

> 
> -- 
> Damien

> #include <stdint.h>
> #include <stdio.h>
> 
> #define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
> 
> #define MI_INSTR(opcode, flags) (((opcode) << 23) | (flags))
> 
> #define MI_NOOP			MI_INSTR(0, 0)
> #define MI_USER_INTERRUPT	MI_INSTR(0x02, 0)
> #define MI_WAIT_FOR_EVENT       MI_INSTR(0x03, 0)
> #define MI_ARB_CHECK            MI_INSTR(0x05, 0)
> #define MI_REPORT_HEAD		MI_INSTR(0x07, 0)
> #define MI_ARB_ON_OFF		MI_INSTR(0x08, 0)
> #define MI_BATCH_BUFFER_END	MI_INSTR(0x0a, 0)
> #define MI_SUSPEND_FLUSH	MI_INSTR(0x0b, 0)
> #define MI_OVERLAY_FLIP		MI_INSTR(0x11, 0)
> #define MI_SET_PREDICATE        MI_INSTR(0x01, 0)
> #define MI_ARB_CHECK            MI_INSTR(0x05, 0)
> #define MI_RS_CONTROL           MI_INSTR(0x06, 0)
> #define MI_URB_ATOMIC_ALLOC     MI_INSTR(0x09, 0)
> #define MI_PREDICATE            MI_INSTR(0x0C, 0)
> #define MI_RS_CONTEXT           MI_INSTR(0x0F, 0)
> #define MI_TOPOLOGY_FILTER      MI_INSTR(0x0D, 0)
> #define MI_LOAD_SCAN_LINES_EXCL MI_INSTR(0x13, 0)
> #define MI_URB_CLEAR            MI_INSTR(0x19, 0)
> #define MI_UPDATE_GTT           MI_INSTR(0x23, 0)
> #define MI_CLFLUSH              MI_INSTR(0x27, 0)
> #define MI_REPORT_PERF_COUNT    MI_INSTR(0x28, 0)
> #define MI_LOAD_REGISTER_MEM    MI_INSTR(0x29, 0)
> #define MI_LOAD_REGISTER_REG    MI_INSTR(0x2A, 0)
> #define MI_RS_STORE_DATA_IMM    MI_INSTR(0x2B, 0)
> #define MI_LOAD_URB_MEM         MI_INSTR(0x2C, 0)
> #define MI_STORE_URB_MEM        MI_INSTR(0x2D, 0)
> #define MI_CONDITIONAL_BATCH_BUFFER_END MI_INSTR(0x36, 0)
> #define MI_SEMAPHORE_MBOX	MI_INSTR(0x16, 1) /* gen6+ */
> #define MI_STORE_DWORD_IMM	MI_INSTR(0x20, 1)
> #define MI_STORE_DWORD_INDEX	MI_INSTR(0x21, 1)
> #define MI_SET_CONTEXT		MI_INSTR(0x18, 0)
> #define MI_LOAD_REGISTER_IMM(x)	MI_INSTR(0x22, 2*(x)-1)
> #define MI_STORE_REGISTER_MEM(x) MI_INSTR(0x24, 2*(x)-1)
> #define MI_BATCH_BUFFER_START	MI_INSTR(0x31, 0)
> #define MI_FLUSH		MI_INSTR(0x04, 0)
> #define MI_DISPLAY_FLIP		MI_INSTR(0x14, 2)
> #define MI_LOAD_SCAN_LINES_INCL MI_INSTR(0x12, 0)
> 
> #define GFX_OP_PIPE_CONTROL(len)	((0x3<<29)|(0x3<<27)|(0x2<<24)|(len-2))
> #define PIPELINE_SELECT                ((0x3<<29)|(0x1<<27)|(0x1<<24)|(0x4<<16))
> #define GFX_OP_3DSTATE_VF_STATISTICS   ((0x3<<29)|(0x1<<27)|(0x0<<24)|(0xB<<16))
> #define MEDIA_VFE_STATE                ((0x3<<29)|(0x2<<27)|(0x0<<24)|(0x0<<16))
> #define  MEDIA_VFE_STATE_MMIO_ACCESS_MASK (0x18)
> #define GPGPU_OBJECT                   ((0x3<<29)|(0x2<<27)|(0x1<<24)|(0x4<<16))
> #define GPGPU_WALKER                   ((0x3<<29)|(0x2<<27)|(0x1<<24)|(0x5<<16))
> #define GFX_OP_3DSTATE_DX9_CONSTANTF_VS \
> 	((0x3<<29)|(0x3<<27)|(0x0<<24)|(0x39<<16))
> #define GFX_OP_3DSTATE_DX9_CONSTANTF_PS \
> 	((0x3<<29)|(0x3<<27)|(0x0<<24)|(0x3A<<16))
> #define GFX_OP_3DSTATE_SO_DECL_LIST \
> 	((0x3<<29)|(0x3<<27)|(0x1<<24)|(0x17<<16))
> 
> #define GFX_OP_3DSTATE_BINDING_TABLE_EDIT_VS \
> 	((0x3<<29)|(0x3<<27)|(0x0<<24)|(0x43<<16))
> #define GFX_OP_3DSTATE_BINDING_TABLE_EDIT_GS \
> 	((0x3<<29)|(0x3<<27)|(0x0<<24)|(0x44<<16))
> #define GFX_OP_3DSTATE_BINDING_TABLE_EDIT_HS \
> 	((0x3<<29)|(0x3<<27)|(0x0<<24)|(0x45<<16))
> #define GFX_OP_3DSTATE_BINDING_TABLE_EDIT_DS \
> 	((0x3<<29)|(0x3<<27)|(0x0<<24)|(0x46<<16))
> #define GFX_OP_3DSTATE_BINDING_TABLE_EDIT_PS \
> 	((0x3<<29)|(0x3<<27)|(0x0<<24)|(0x47<<16))
> 
> #define MFX_WAIT  ((0x3<<29)|(0x1<<27)|(0x0<<16))
> 
> #define COLOR_BLT     ((0x2<<29)|(0x40<<22))
> #define SRC_COPY_BLT  ((0x2<<29)|(0x43<<22))
> 
> uint32_t opcodes[] = {
> 	MI_NOOP,
> 	MI_USER_INTERRUPT,
> 	MI_WAIT_FOR_EVENT,
> 	MI_ARB_CHECK,
> 	MI_REPORT_HEAD,
> 	MI_SUSPEND_FLUSH,
> 	MI_SEMAPHORE_MBOX,
> 	MI_STORE_DWORD_INDEX,
> 	MI_LOAD_REGISTER_IMM(1),
> 	MI_STORE_REGISTER_MEM(1),
> 	MI_LOAD_REGISTER_MEM,
> 	MI_BATCH_BUFFER_START,
> 	MI_FLUSH,
> 	MI_ARB_ON_OFF,
> 	MI_PREDICATE,
> 	MI_TOPOLOGY_FILTER,
> 	MI_DISPLAY_FLIP,
> 	MI_SET_CONTEXT,
> 	MI_URB_CLEAR,
> 	MI_STORE_DWORD_IMM,
> 	MI_UPDATE_GTT,
> 	MI_CLFLUSH,
> 	MI_REPORT_PERF_COUNT,
> 	MI_CONDITIONAL_BATCH_BUFFER_END,
> 	GFX_OP_3DSTATE_VF_STATISTICS,
> 	PIPELINE_SELECT,
> 	MEDIA_VFE_STATE,
> 	GPGPU_OBJECT,
> 	GPGPU_WALKER,
> 	GFX_OP_3DSTATE_SO_DECL_LIST,
> 	GFX_OP_PIPE_CONTROL(5),
> 	MI_LOAD_SCAN_LINES_INCL,
> 	MI_LOAD_SCAN_LINES_EXCL,
> 	MI_LOAD_REGISTER_REG,
> 	MI_RS_STORE_DATA_IMM,
> 	MI_LOAD_URB_MEM,
> 	MI_STORE_URB_MEM,
> 	GFX_OP_3DSTATE_DX9_CONSTANTF_VS,
> 	GFX_OP_3DSTATE_DX9_CONSTANTF_PS,
> 	GFX_OP_3DSTATE_BINDING_TABLE_EDIT_VS,
> 	GFX_OP_3DSTATE_BINDING_TABLE_EDIT_GS,
> 	GFX_OP_3DSTATE_BINDING_TABLE_EDIT_HS,
> 	GFX_OP_3DSTATE_BINDING_TABLE_EDIT_DS,
> 	GFX_OP_3DSTATE_BINDING_TABLE_EDIT_PS,
> };
> 
> #define STD_MI_OPCODE_MASK  0xFF800000
> #define STD_3D_OPCODE_MASK  0xFFFF0000
> #define STD_2D_OPCODE_MASK  0xFFC00000
> #define STD_MFX_OPCODE_MASK 0xFFFF0000
> #define CMD_HASH_MASK STD_MI_OPCODE_MASK
> 
> int main(void)
> {
> 	int i;
> 
> 	for (i = 0; i < ARRAY_SIZE(opcodes); i++)
> 		printf("%08x\n", opcodes[i] & CMD_HASH_MASK);
> 
> 	return 0;
> }