smalloc: print debug info on oom error

Provide more details about the request and the state of the memory pools
when smalloc encounters an oom situation.

diff --git a/smalloc.c b/smalloc.c
index a2ad25a0a0d03bf5010c743325ed17e594e0fb83..c1ae08bd26fa3e67e294c99430a364508e6c46fc 100644 (file)
--- a/smalloc.c
+++ b/smalloc.c
@@ -48,6 +48,12 @@ struct block_hdr {
 #endif
 };
 
+/*
+ * This suppresses the voluminous potential bitmap printout when
+ * smalloc encounters an OOM error
+ */
+static const bool enable_smalloc_debug = false;
+
 static struct pool mp[MAX_POOLS];
 static unsigned int nr_pools;
 static unsigned int last_pool;
@@ -387,10 +393,9 @@ fail:
        return ret;
 }
 
-static void *smalloc_pool(struct pool *pool, size_t size)
+static size_t size_to_alloc_size(size_t size)
 {
        size_t alloc_size = size + sizeof(struct block_hdr);
-       void *ptr;
 
        /*
         * Round to int alignment, so that the postred pointer will
@@ -401,6 +406,14 @@ static void *smalloc_pool(struct pool *pool, size_t size)
        alloc_size = (alloc_size + int_mask) & ~int_mask;
 #endif
 
+       return alloc_size;
+}
+
+static void *smalloc_pool(struct pool *pool, size_t size)
+{
+       size_t alloc_size = size_to_alloc_size(size);
+       void *ptr;
+
        ptr = __smalloc_pool(pool, alloc_size);
        if (ptr) {
                struct block_hdr *hdr = ptr;
@@ -415,6 +428,72 @@ static void *smalloc_pool(struct pool *pool, size_t size)
        return ptr;
 }
 
+static void smalloc_print_bitmap(struct pool *pool)
+{
+       size_t nr_blocks = pool->nr_blocks;
+       unsigned int *bitmap = pool->bitmap;
+       unsigned int i, j;
+       char *buffer;
+
+       if (!enable_smalloc_debug)
+               return;
+
+       buffer = malloc(SMALLOC_BPI + 1);
+       if (!buffer)
+               return;
+       buffer[SMALLOC_BPI] = '\0';
+
+       for (i = 0; i < nr_blocks; i++) {
+               unsigned int line = bitmap[i];
+
+               /* skip completely full lines */
+               if (line == -1U)
+                       continue;
+
+               for (j = 0; j < SMALLOC_BPI; j++)
+                       if ((1 << j) & line)
+                               buffer[SMALLOC_BPI-1-j] = '1';
+                       else
+                               buffer[SMALLOC_BPI-1-j] = '0';
+
+               log_err("smalloc: bitmap %5u, %s\n", i, buffer);
+       }
+
+       free(buffer);
+}
+
+void smalloc_debug(size_t size)
+{
+       unsigned int i;
+       size_t alloc_size = size_to_alloc_size(size);
+       size_t alloc_blocks;
+
+       alloc_blocks = size_to_blocks(alloc_size);
+
+       if (size)
+               log_err("smalloc: size = %lu, alloc_size = %lu, blocks = %lu\n",
+                       (unsigned long) size, (unsigned long) alloc_size,
+                       (unsigned long) alloc_blocks);
+       for (i = 0; i < nr_pools; i++) {
+               log_err("smalloc: pool %u, free/total blocks %u/%u\n", i,
+                       (unsigned int) (mp[i].free_blocks),
+                       (unsigned int) (mp[i].nr_blocks*sizeof(unsigned int)*8));
+               if (size && mp[i].free_blocks >= alloc_blocks) {
+                       void *ptr = smalloc_pool(&mp[i], size);
+                       if (ptr) {
+                               sfree(ptr);
+                               last_pool = i;
+                               log_err("smalloc: smalloc_pool %u succeeded\n", i);
+                       } else {
+                               log_err("smalloc: smalloc_pool %u failed\n", i);
+                               log_err("smalloc: next_non_full=%u, nr_blocks=%u\n",
+                                       (unsigned int) mp[i].next_non_full, (unsigned int) mp[i].nr_blocks);
+                               smalloc_print_bitmap(&mp[i]);
+                       }
+               }
+       }
+}
+
 void *smalloc(size_t size)
 {
        unsigned int i, end_pool;
@@ -445,6 +524,7 @@ void *smalloc(size_t size)
 
        log_err("smalloc: OOM. Consider using --alloc-size to increase the "
                "shared memory available.\n");
+       smalloc_debug(size);
        return NULL;
 }
 

diff --git a/smalloc.h b/smalloc.h
index 8df10e6f67fd401defbb99b3e68ab0ab15a9d619..1f7716f45a8d0308f4bcee85225382052d23d08f 100644 (file)
--- a/smalloc.h
+++ b/smalloc.h
@@ -9,6 +9,7 @@ extern void sfree(void *);
 extern char *smalloc_strdup(const char *);
 extern void sinit(void);
 extern void scleanup(void);
+extern void smalloc_debug(size_t);
 
 extern unsigned int smalloc_pool_size;