[PATCH v7 3/5] erofs-utils: mkfs: add --workers=# parameter

[Gao Xiang]

From: Yifan Zhao <zhaoyifan at sjtu.edu.cn>

This patch introduces `--workers=#` parameter for the incoming
multi-threaded compression support.

It also introduces a concept called `segment size` to split large
inodes for multi-threaded compression, which has the fixed value
16MiB and cannot be modified for now.

Signed-off-by: Yifan Zhao <zhaoyifan at sjtu.edu.cn>
Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>
---
 include/erofs/config.h |  4 ++++
 lib/config.c           |  4 ++++
 mkfs/main.c            | 23 +++++++++++++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/include/erofs/config.h b/include/erofs/config.h
index 73e3ac2..d2f91ff 100644
--- a/include/erofs/config.h
+++ b/include/erofs/config.h
@@ -75,6 +75,10 @@ struct erofs_configure {
 	char c_force_chunkformat;
 	/* < 0, xattr disabled and INT_MAX, always use inline xattrs */
 	int c_inline_xattr_tolerance;
+#ifdef EROFS_MT_ENABLED
+	u64 c_segment_size;
+	u32 c_mt_workers;
+#endif
 
 	u32 c_pclusterblks_max, c_pclusterblks_def, c_pclusterblks_packed;
 	u32 c_max_decompressed_extent_bytes;
diff --git a/lib/config.c b/lib/config.c
index 947a183..2530274 100644
--- a/lib/config.c
+++ b/lib/config.c
@@ -38,6 +38,10 @@ void erofs_init_configure(void)
 	cfg.c_pclusterblks_max = 1;
 	cfg.c_pclusterblks_def = 1;
 	cfg.c_max_decompressed_extent_bytes = -1;
+#ifdef EROFS_MT_ENABLED
+	cfg.c_segment_size = 16ULL * 1024 * 1024;
+	cfg.c_mt_workers = 1;
+#endif
 
 	erofs_stdout_tty = isatty(STDOUT_FILENO);
 }
diff --git a/mkfs/main.c b/mkfs/main.c
index 8a68a72..126a049 100644
--- a/mkfs/main.c
+++ b/mkfs/main.c
@@ -77,6 +77,9 @@ static struct option long_options[] = {
 #ifdef HAVE_LIBLZMA
 	{"unlzma", optional_argument, NULL, 519},
 	{"unxz", optional_argument, NULL, 519},
+#endif
+#ifdef EROFS_MT_ENABLED
+	{"workers", required_argument, NULL, 520},
 #endif
 	{0, 0, 0, 0},
 };
@@ -178,6 +181,9 @@ static void usage(int argc, char **argv)
 #ifdef HAVE_LIBLZMA
 		" --unxz[=X]            try to filter the tarball stream through xz/lzma/lzip\n"
 		"                       (and optionally dump the raw stream to X together)\n"
+#endif
+#ifdef EROFS_MT_ENABLED
+		" --workers=#           set the number of worker threads to # (default=1)\n"
 #endif
 		" --xattr-prefix=X      X=extra xattr name prefix\n"
 		" --mount-point=X       X=prefix of target fs path (default: /)\n"
@@ -660,6 +666,23 @@ static int mkfs_parse_options_cfg(int argc, char *argv[])
 				erofstar.dumpfile = strdup(optarg);
 			tarerofs_decoder = EROFS_IOS_DECODER_GZIP + (opt - 518);
 			break;
+#ifdef EROFS_MT_ENABLED
+		case 520: {
+			unsigned int processors;
+
+			cfg.c_mt_workers = strtoul(optarg, &endptr, 0);
+			if (errno || *endptr != '\0') {
+				erofs_err("invalid worker number %s", optarg);
+				return -EINVAL;
+			}
+
+			processors = erofs_get_available_processors();
+			if (cfg.c_mt_workers > processors)
+				erofs_warn("the number of workers %d is more than the number of processors %d, performance may be impacted.",
+					   cfg.c_mt_workers, processors);
+			break;
+		}
+#endif
 		case 'V':
 			version();
 			exit(0);
-- 
2.39.3