[PATCH v1 2/3] policycoreutils/setfiles: use all CPU cores by default

[jboero <boeroboy@gmail.com>]

From: Johnny Boero <boeroboy@gmail.com>

setfiles(8) and restorecon(8) have supported parallel relabeling via -T
since commit 93902fc8b0b0 ("setfiles/restorecon: support parallel
relabeling"), but default to a single thread, so anything that does not
pass -T explicitly relabels on one core.

That is most callers.  RPM scriptlets, fixfiles(8) and hand-run
restorecon invocations all use the default, and on a machine with a high
core count the result is a long, almost entirely idle relabel: a package
upgrade on an 88 core system spent hours in restorecon with 87 cores
doing nothing.

Default nthreads to 0, i.e. one thread per available CPU core.  The
relabeling is already serialized where it needs to be, and -T 1 remains
available for callers that want the previous behaviour.

Relabeling /usr/share (~588k files, dry run) on an 88 core system:

  -T 1   20.43s
  -T 0   15.78s

Link: https://github.com/SELinuxProject/selinux/issues/489
Signed-off-by: Johnny Boero <boeroboy@gmail.com>
---
 policycoreutils/setfiles/restorecon.8 | 2 +-
 policycoreutils/setfiles/setfiles.8   | 2 +-
 policycoreutils/setfiles/setfiles.c   | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/policycoreutils/setfiles/restorecon.8 b/policycoreutils/setfiles/restorecon.8
index 443f29ab..8d7b46f0 100644
--- a/policycoreutils/setfiles/restorecon.8
+++ b/policycoreutils/setfiles/restorecon.8
@@ -186,7 +186,7 @@ from crossing file system boundaries.
 use up to
 .I nthreads
 threads.  Specify 0 to create as many threads as there are available
-CPU cores; 1 to use only a single thread (default); or any positive
+CPU cores (default); 1 to use only a single thread; or any positive
 number to use the given number of threads (if possible).
 .TP
 .SH "ARGUMENTS"
diff --git a/policycoreutils/setfiles/setfiles.8 b/policycoreutils/setfiles/setfiles.8
index b521df22..53cb97cc 100644
--- a/policycoreutils/setfiles/setfiles.8
+++ b/policycoreutils/setfiles/setfiles.8
@@ -191,7 +191,7 @@ produces input suitable for this mode.
 use up to
 .I nthreads
 threads.  Specify 0 to create as many threads as there are available
-CPU cores; 1 to use only a single thread (default); or any positive
+CPU cores (default); 1 to use only a single thread; or any positive
 number to use the given number of threads (if possible).
 .TP
 .B \-A
diff --git a/policycoreutils/setfiles/setfiles.c b/policycoreutils/setfiles/setfiles.c
index c86cc0c9..4c860755 100644
--- a/policycoreutils/setfiles/setfiles.c
+++ b/policycoreutils/setfiles/setfiles.c
@@ -168,7 +168,7 @@ int main(int argc, char **argv)
 	const char *input_filename = NULL;
 	int use_input_file = 0;
 	char *buf = NULL;
-	size_t buf_len = 0, nthreads = 1;
+	size_t buf_len = 0, nthreads = 0;
 	const char *base;
 	int errors = 0;
 	const char *ropts = "ce:f:hijIDlmno:pqrsvFURW0xT:";
-- 
2.55.0