Increase default disk cache to 16 MiB

Author: amadvance

HISTORY

@@ -4,6 +4,7 @@ SnapRAID HISTORY
 12.1 2022/01
 ============
  * Reduce stack usage to work in enviromnents with limited stack size, like MUSL.
+ * Increase the default disk cache from 8 MiB to 16 MiB.
 
 12.0 2021/12
 ============

cmdline/io.c

@@ -879,9 +879,9 @@ void io_init(struct snapraid_io* io, struct snapraid_state* state,
 
 #if HAVE_THREAD
 	if (io_cache == 0) {
-		/* default is 8 MiB of cache */
+		/* default is 16 MiB of cache */
 		/* this seems to be a good tradeoff between speed and memory usage */
-		io->io_max = 8 * 1024 * 1024 / state->block_size;
+		io->io_max = 16 * 1024 * 1024 / state->block_size;
 		if (io->io_max < IO_MIN)
 			io->io_max = IO_MIN;
 		if (io->io_max > IO_MAX)

cmdline/io.h

@@ -35,8 +35,8 @@
  *  4  - 452 MB/s, CPU 54%, speed 118%
  *  8  - 487 MB/s, CPU 60%, speed 128%
  * 16  - 505 MB/s, CPU 63%, speed 132%
- * 32  - 520 MB/s, CPU 64%, speed 136%
- * 64  - 524 MB/s, CPU 65%, speed 137%
+ * 32  - 520 MB/s, CPU 64%, speed 136% [SnapRAID <= 12.0]
+ * 64  - 524 MB/s, CPU 65%, speed 137% [SnapRAID > 12.0]
  * 128 - 525 MB/s, CPU 66%, speed 138%
  */
 #define IO_MIN 3 /* required by writers, readers can work also with 2 */