Add default subbuf sizes getter functions

[lttng-tools.git] / src / common / defaults.c

diff --git a/src/common/defaults.c b/src/common/defaults.c
new file mode 100644 (file)
index 0000000..ccdbaf4
--- /dev/null
+++ b/src/common/defaults.c
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2012 - Simon Marchi <simon.marchi@polymtl.ca>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License, version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stddef.h>
+#include <unistd.h>
+
+#include "defaults.h"
+#include "macros.h"
+
+size_t default_channel_subbuf_size;
+size_t default_metadata_subbuf_size;
+size_t default_kernel_channel_subbuf_size;
+size_t default_ust_channel_subbuf_size;
+
+static void __attribute__((constructor)) init_defaults(void)
+{
+       /*
+        * The libringbuffer won't accept subbuf sizes smaller than the page size.
+        * If the default subbuf size is smaller, replace it by the page size.
+        */
+       long page_size = sysconf(_SC_PAGESIZE);
+
+       if (page_size < 0) {
+               page_size = 0;
+       }
+
+       default_channel_subbuf_size =
+               max(DEFAULT_CHANNEL_SUBBUF_SIZE, page_size);
+       default_metadata_subbuf_size =
+               max(DEFAULT_METADATA_SUBBUF_SIZE, page_size);
+       default_kernel_channel_subbuf_size =
+               max(DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE, page_size);
+       default_ust_channel_subbuf_size =
+               max(DEFAULT_UST_CHANNEL_SUBBUF_SIZE, page_size);
+}