Merge remote-tracking branch 'remotes/stsquad/tags/pull-mttcg-fixups-for-rc2-280317...

[mirror_qemu.git] / util / oslib-posix.c

diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 956f66ab4a5caf6a7a59586283d341e48a964147..4d9189e9efcfd034a92f5358a7d0044e558f7d29 100644 (file)
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -55,7 +55,7 @@
 #include "qemu/error-report.h"
 #endif
 
-#define MAX_MEM_PREALLOC_THREAD_COUNT (MIN(sysconf(_SC_NPROCESSORS_ONLN), 16))
+#define MAX_MEM_PREALLOC_THREAD_COUNT 16
 
 struct MemsetThread {
     char *addr;
@@ -361,7 +361,19 @@ static void *do_touch_pages(void *arg)
         memset_thread_failed = true;
     } else {
         for (i = 0; i < numpages; i++) {
-            memset(addr, 0, 1);
+            /*
+             * Read & write back the same value, so we don't
+             * corrupt existing user/app data that might be
+             * stored.
+             *
+             * 'volatile' to stop compiler optimizing this away
+             * to a no-op
+             *
+             * TODO: get a better solution from kernel so we
+             * don't need to write at all so we don't cause
+             * wear on the storage backing the region...
+             */
+            *(volatile char *)addr = *addr;
             addr += hpagesize;
         }
     }
@@ -369,6 +381,18 @@ static void *do_touch_pages(void *arg)
     return NULL;
 }
 
+static inline int get_memset_num_threads(int smp_cpus)
+{
+    long host_procs = sysconf(_SC_NPROCESSORS_ONLN);
+    int ret = 1;
+
+    if (host_procs > 0) {
+        ret = MIN(MIN(host_procs, MAX_MEM_PREALLOC_THREAD_COUNT), smp_cpus);
+    }
+    /* In case sysconf() fails, we fall back to single threaded */
+    return ret;
+}
+
 static bool touch_all_pages(char *area, size_t hpagesize, size_t numpages,
                             int smp_cpus)
 {
@@ -377,7 +401,7 @@ static bool touch_all_pages(char *area, size_t hpagesize, size_t numpages,
     int i = 0;
 
     memset_thread_failed = false;
-    memset_num_threads = MIN(smp_cpus, MAX_MEM_PREALLOC_THREAD_COUNT);
+    memset_num_threads = get_memset_num_threads(smp_cpus);
     memset_thread = g_new0(MemsetThread, memset_num_threads);
     numpages_per_thread = (numpages / memset_num_threads);
     size_per_thread = (hpagesize * numpages_per_thread);
@@ -697,8 +721,6 @@ void sigaction_invoke(struct sigaction *action,
         si.si_pid = info->ssi_pid;
         si.si_status = info->ssi_status;
         si.si_uid = info->ssi_uid;
-    } else if (info->ssi_signo == SIGIO) {
-        si.si_band = info->ssi_band;
     }
     action->sa_sigaction(info->ssi_signo, &si, NULL);
 }