ARCv2: guard SLC DMA ops with spinlock
SLC maintenance ops need to be serialized by software as there is no
inherent buffering / quequing of aux commands. It can silently ignore a
new aux operation if previous one is still ongoing (SLC_CTRL_BUSY)
So gaurd the SLC op using a spin lock
The spin lock doesn't seem to be contended even in heavy workloads such
as iperf. On FPGA @ 75 MHz.
[1] Before this change:
============================================================
# iperf -c 10.42.0.1
------------------------------------------------------------
Client connecting to 10.42.0.1, TCP port 5001
TCP window size: 43.8 KByte (default)
------------------------------------------------------------
[ 3] local 10.42.0.110 port 38935 connected with 10.42.0.1 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 48.4 MBytes 40.6 Mbits/sec
============================================================
[2] After this change:
============================================================
# iperf -c 10.42.0.1
------------------------------------------------------------
Client connecting to 10.42.0.1, TCP port 5001
TCP window size: 43.8 KByte (default)
------------------------------------------------------------
[ 3] local 10.42.0.243 port 60248 connected with 10.42.0.1 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 47.5 MBytes 39.8 Mbits/sec
# iperf -c 10.42.0.1
------------------------------------------------------------
Client connecting to 10.42.0.1, TCP port 5001
TCP window size: 43.8 KByte (default)
------------------------------------------------------------
[ 3] local 10.42.0.243 port 60249 connected with 10.42.0.1 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 54.9 MBytes 46.0 Mbits/sec
============================================================
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: arc-linux-dev@synopsys.com
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
projects / linux-2.6-block.git / commit