Reduce realloc syscall overhead for FT2232 and bitbang
FT2232 ran realloc() for every executed command. Start with a big enough
buffer and don't touch buffer size unless it needs to grow.
Bitbang was slightly better: It only ran realloc() if buffer size
changed. Still, the solution above improves performance and reliability.
Corresponding to flashrom svn r780.
Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Sean Nelson <audiohacked@gmail.com>
diff --git a/bitbang_spi.c b/bitbang_spi.c
index 0f1f7ed..abf5530 100644
--- a/bitbang_spi.c
+++ b/bitbang_spi.c
@@ -87,14 +87,16 @@
static unsigned char *bufout = NULL;
static unsigned char *bufin = NULL;
static int oldbufsize = 0;
- int bufsize = max(writecnt + readcnt, 260);
+ int bufsize;
int i;
/* Arbitrary size limitation here. We're only constrained by memory. */
if (writecnt > 65536 || readcnt > 65536)
return SPI_INVALID_LENGTH;
- if (bufsize != oldbufsize) {
+ bufsize = max(writecnt + readcnt, 260);
+ /* Never shrink. realloc() calls are expensive. */
+ if (bufsize > oldbufsize) {
bufout = realloc(bufout, bufsize);
if (!bufout) {
fprintf(stderr, "Out of memory!\n");
@@ -109,6 +111,7 @@
free(bufout);
exit(1);
}
+ oldbufsize = bufsize;
}
memcpy(bufout, writearr, writecnt);
diff --git a/ft2232_spi.c b/ft2232_spi.c
index aa00753..d565a6f 100644
--- a/ft2232_spi.c
+++ b/ft2232_spi.c
@@ -200,14 +200,22 @@
static unsigned char *buf = NULL;
/* failed is special. We use bitwise ops, but it is essentially bool. */
int i = 0, ret = 0, failed = 0;
+ int bufsize;
+ static int oldbufsize = 0;
if (writecnt > 65536 || readcnt > 65536)
return SPI_INVALID_LENGTH;
- buf = realloc(buf, writecnt + readcnt + 100);
- if (!buf) {
- fprintf(stderr, "Out of memory!\n");
- exit(1); // -1
+ /* buf is not used for the response from the chip. */
+ bufsize = max(writecnt + 9, 260 + 9);
+ /* Never shrink. realloc() calls are expensive. */
+ if (bufsize > oldbufsize) {
+ buf = realloc(buf, bufsize);
+ if (!buf) {
+ fprintf(stderr, "Out of memory!\n");
+ exit(1);
+ }
+ oldbufsize = bufsize;
}
/*