Hi, Ruifeng > -----Original Message----- > From: Ruifeng Wang <[email protected]> > Sent: Tuesday, June 1, 2021 11:31 > To: Raslan Darawsheh <[email protected]>; Matan Azrad > <[email protected]>; Shahaf Shuler <[email protected]>; Slava Ovsiienko > <[email protected]> > Cc: [email protected]; [email protected]; [email protected]; > [email protected]; Ruifeng Wang <[email protected]>; > [email protected] > Subject: [PATCH 1/2] net/mlx5: remove redundant operations > > Some operations on mask are redundant and can be removed. > The change yielded 1.6% performance gain on N1SDP. > On ThunderX2, slight performance uplift was also observed. > > Fixes: 570acdb1da8a ("net/mlx5: add vectorized Rx/Tx burst for ARM") > Cc: [email protected] > > Signed-off-by: Ruifeng Wang <[email protected]> > --- > drivers/net/mlx5/mlx5_rxtx_vec_neon.h | 9 +-------- > 1 file changed, 1 insertion(+), 8 deletions(-) > > diff --git a/drivers/net/mlx5/mlx5_rxtx_vec_neon.h > b/drivers/net/mlx5/mlx5_rxtx_vec_neon.h > index 2234fbe6b2..98a75b09c6 100644 > --- a/drivers/net/mlx5/mlx5_rxtx_vec_neon.h > +++ b/drivers/net/mlx5/mlx5_rxtx_vec_neon.h > @@ -768,18 +768,11 @@ rxq_cq_process_v(struct mlx5_rxq_data *rxq, > volatile struct mlx5_cqe *cq, > comp_mask), 0)) / > (sizeof(uint16_t) * 8); > /* D.6 mask out entries after the compressed CQE. */ > - mask = vcreate_u16(comp_idx < > MLX5_VPMD_DESCS_PER_LOOP ? > - -1UL >> (comp_idx * sizeof(uint16_t) * 8) : > - 0); > - invalid_mask = vorr_u16(invalid_mask, mask); > + invalid_mask = vorr_u16(invalid_mask, comp_mask);
Mmmm... I'm not sure we can drop the masking compressed (and following) CQE skip. Let's consider the completion scenario (the series of 4 CQEs, each element is 64B long) 0: normal uncompressed CQE, ownership OK, format uncompressed, opcode OK, no error 1: compressed CQE, ownership OK, format compressed, opcode OK, no error 2: miniCQE array, format can be any!!, may be discovered as ownership OK, format uncompressed, opcode OK, no error 3: miniCQE array, format can be any!!, may be discovered as ownership OK, format uncompressed, opcode OK, no error Obviously, we should unconditionally mask out 2 and 3, regardless of recognized their formats/opcode/error/etc. I think we can get the diff above and skip diff below: > /* D.7 count non-compressed valid CQEs. */ > n = __builtin_clzl(vget_lane_u64(vreinterpret_u64_u16( > invalid_mask), 0)) / (sizeof(uint16_t) * 8); > nocmp_n += n; > - /* D.2 get the final invalid mask. */ > - mask = vcreate_u16(n < MLX5_VPMD_DESCS_PER_LOOP ? > - -1UL >> (n * sizeof(uint16_t) * 8) : 0); > - invalid_mask = vorr_u16(invalid_mask, mask); and get the correct final invalid_mask - all compressed and invalid CQEs and following ones will be masked out. With best regards, Slava
