From 1cc8febf4c8cdf35afeef4623daeb65fec462d0f Mon Sep 17 00:00:00 2001 From: Andrew Rybchenko Date: Mon, 23 Mar 2015 15:45:39 +0000 Subject: [PATCH] sfxge: add barriers to BAR write macros In theory the barriers are required to cope with write combining and reordering. Two barriers are added (sometimes merged to one): 1. Before the first write to guarantee that previous writes to the region have been done 2. Before the last write to guarantee that write to the last dword/qword is done after previous writes Barriers are inserted before in the assumption that it is better to postpone barriers as much as it is possible (more chances that the operation has already been already done and barrier does not stall CPU). On x86 and amd64 bus space write barriers are just compiler memory barriers which are definitely required. Sponsored by: Solarflare Communications, Inc. Differential Revision: https://reviews.freebsd.org/D2077 --- sys/dev/sfxge/common/efsys.h | 64 ++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) diff --git a/sys/dev/sfxge/common/efsys.h b/sys/dev/sfxge/common/efsys.h index e4afb45971a..983ade71c10 100644 --- a/sys/dev/sfxge/common/efsys.h +++ b/sys/dev/sfxge/common/efsys.h @@ -786,6 +786,14 @@ typedef struct efsys_bar_s { EFSYS_PROBE2(bar_writed, unsigned int, (_offset), \ uint32_t, (_edp)->ed_u32[0]); \ \ + /* \ + * Make sure that previous writes to the dword have \ + * been done. It should be cheaper than barrier just \ + * after the write below. \ + */ \ + bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\ + (_offset), sizeof (efx_dword_t), \ + BUS_SPACE_BARRIER_WRITE); \ bus_space_write_stream_4((_esbp)->esb_tag, \ (_esbp)->esb_handle, \ (_offset), (_edp)->ed_u32[0]); \ @@ -809,6 +817,14 @@ typedef struct efsys_bar_s { uint32_t, (_eqp)->eq_u32[1], \ uint32_t, (_eqp)->eq_u32[0]); \ \ + /* \ + * Make sure that previous writes to the qword have \ + * been done. It should be cheaper than barrier just \ + * after the write below. \ + */ \ + bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\ + (_offset), sizeof (efx_qword_t), \ + BUS_SPACE_BARRIER_WRITE); \ bus_space_write_stream_8((_esbp)->esb_tag, \ (_esbp)->esb_handle, \ (_offset), (_eqp)->eq_u64[0]); \ @@ -829,9 +845,25 @@ typedef struct efsys_bar_s { uint32_t, (_eqp)->eq_u32[1], \ uint32_t, (_eqp)->eq_u32[0]); \ \ + /* \ + * Make sure that previous writes to the qword have \ + * been done. It should be cheaper than barrier just \ + * after the last write below. \ + */ \ + bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\ + (_offset), sizeof (efx_qword_t), \ + BUS_SPACE_BARRIER_WRITE); \ bus_space_write_stream_4((_esbp)->esb_tag, \ (_esbp)->esb_handle, \ (_offset), (_eqp)->eq_u32[0]); \ + /* \ + * It should be guaranteed that the last dword comes \ + * the last, so barrier entire qword to be sure that \ + * neither above nor below writes are reordered. \ + */ \ + bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\ + (_offset), sizeof (efx_qword_t), \ + BUS_SPACE_BARRIER_WRITE); \ bus_space_write_stream_4((_esbp)->esb_tag, \ (_esbp)->esb_handle, \ (_offset) + 4, (_eqp)->eq_u32[1]); \ @@ -858,9 +890,25 @@ typedef struct efsys_bar_s { uint32_t, (_eop)->eo_u32[1], \ uint32_t, (_eop)->eo_u32[0]); \ \ + /* \ + * Make sure that previous writes to the oword have \ + * been done. It should be cheaper than barrier just \ + * after the last write below. \ + */ \ + bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\ + (_offset), sizeof (efx_oword_t), \ + BUS_SPACE_BARRIER_WRITE); \ bus_space_write_stream_8((_esbp)->esb_tag, \ (_esbp)->esb_handle, \ (_offset), (_eop)->eo_u64[0]); \ + /* \ + * It should be guaranteed that the last qword comes \ + * the last, so barrier entire oword to be sure that \ + * neither above nor below writes are reordered. \ + */ \ + bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\ + (_offset), sizeof (efx_oword_t), \ + BUS_SPACE_BARRIER_WRITE); \ bus_space_write_stream_8((_esbp)->esb_tag, \ (_esbp)->esb_handle, \ (_offset) + 8, (_eop)->eo_u64[1]); \ @@ -888,6 +936,14 @@ typedef struct efsys_bar_s { uint32_t, (_eop)->eo_u32[1], \ uint32_t, (_eop)->eo_u32[0]); \ \ + /* \ + * Make sure that previous writes to the oword have \ + * been done. It should be cheaper than barrier just \ + * after the last write below. \ + */ \ + bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\ + (_offset), sizeof (efx_oword_t), \ + BUS_SPACE_BARRIER_WRITE); \ bus_space_write_stream_4((_esbp)->esb_tag, \ (_esbp)->esb_handle, \ (_offset), (_eop)->eo_u32[0]); \ @@ -897,6 +953,14 @@ typedef struct efsys_bar_s { bus_space_write_stream_4((_esbp)->esb_tag, \ (_esbp)->esb_handle, \ (_offset) + 8, (_eop)->eo_u32[2]); \ + /* \ + * It should be guaranteed that the last dword comes \ + * the last, so barrier entire oword to be sure that \ + * neither above nor below writes are reordered. \ + */ \ + bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\ + (_offset), sizeof (efx_oword_t), \ + BUS_SPACE_BARRIER_WRITE); \ bus_space_write_stream_4((_esbp)->esb_tag, \ (_esbp)->esb_handle, \ (_offset) + 12, (_eop)->eo_u32[3]); \