[Xen-devel] [PATCH V2] xs: set read_thread stacksize

[Simon Rowe <simon.rowe@xxxxxxxxxxxxx>]

xs_watch() creates a thread to wake watchers using default attributes. The
stacksize can be quite large (8 MB on Linux), applications that link against
xenstore end up having a larger memory footprint than necessary.

Signed-off-by: Simon Rowe <simon.rowe@xxxxxxxxxxxxx>

---
Changed since v1:
  * remove test for _POSIX_THREAD_ATTR_STACKSIZE
  * use define for constant

diff -r 52ffce7a036e -r 2d0a29ab3f91 tools/xenstore/xs.c
--- a/tools/xenstore/xs.c       Tue May 29 11:36:36 2012 +0100
+++ b/tools/xenstore/xs.c       Wed May 30 13:41:07 2012 +0100
@@ -702,14 +702,29 @@ bool xs_watch(struct xs_handle *h, const
        struct iovec iov[2];
 
 #ifdef USE_PTHREAD
+#define READ_THREAD_STACKSIZE (16 * 1024)
+
        /* We dynamically create a reader thread on demand. */
        mutex_lock(&h->request_mutex);
        if (!h->read_thr_exists) {
-               if (pthread_create(&h->read_thr, NULL, read_thread, h) != 0) {
+               pthread_attr_t attr;
+
+               if (pthread_attr_init(&attr) != 0) {
+                       mutex_unlock(&h->request_mutex);
+                       return false;
+               }
+               if (pthread_attr_setstacksize(&attr, READ_THREAD_STACKSIZE) != 
0) {
+                       pthread_attr_destroy(&attr);
+                       mutex_unlock(&h->request_mutex);
+                       return false;
+               }
+               if (pthread_create(&h->read_thr, &attr, read_thread, h) != 0) {
+                       pthread_attr_destroy(&attr);
                        mutex_unlock(&h->request_mutex);
                        return false;
                }
                h->read_thr_exists = 1;
+               pthread_attr_destroy(&attr);
        }
        mutex_unlock(&h->request_mutex);
 #endif

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