mtd-utils: flash_speed: Measure read while write latency

The Read While Write (RWW) feature allows to perform reads from the
flash array into cache while a program (from cache) or an erase
operation happens, provided that the two areas are located on different
banks.

The main benefit is the possible reduced latency when requesting to read
a page while a much longer operation is ongoing, like a write or an
erase.

We can try to compare the positive impact of such a feature by enhancing
the flash_speed test tool with the following test:
- Measure the time taken by an eraseblock write in parallel with an
  eraseblock read.
- Measure when the read operation ends.
- Compare the two to get the latency saved with the RWW feature.

To be sure the mtd_write actually starts (and acquires the necessary
locks) before the mtd_read does, we use SCHED_FIFO at rather high
(arbitrary) priorities, respectively 42 and 41.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 4 insertions, 1 deletions

diff --git a/tests/mtd-tests/Makemodule.am b/tests/mtd-tests/Makemodule.am
index d849e3c..d02e9e4 100644
--- a/tests/mtd-tests/Makemodule.am
+++ b/tests/mtd-tests/Makemodule.am
@@ -7,9 +7,12 @@ flash_stress_LDADD = libmtd.a
 flash_stress_CPPFLAGS = $(AM_CPPFLAGS)
 
 flash_speed_SOURCES = tests/mtd-tests/flash_speed.c
-flash_speed_LDADD = libmtd.a
+flash_speed_LDADD = libmtd.a $(PTHREAD_LIBS)
 flash_speed_CPPFLAGS = $(AM_CPPFLAGS)
 
+flash_speed_LDADD += $(PTHREAD_CFLAGS)
+flash_speed_CPPFLAGS += $(PTHREAD_CFLAGS)
+
 nandbiterrs_SOURCES = tests/mtd-tests/nandbiterrs.c
 nandbiterrs_LDADD = libmtd.a
 nandbiterrs_CPPFLAGS = $(AM_CPPFLAGS)