Slab allocator update

Unused slabs which get recycled are no longer reinitialized from scratch if their chunk size matches what the allocator needed. If the chunk size matches, the list of available chunks is left unchanged, and just the various counters are reset.

Added __get_slab_stats() function.

Added support for global __slab_purge_threshold tuning variable.

Added a short test program for the slab allocator.

The malloc-test program was linked against the wrong object file in GNUmakefile.68k. Fixed.

library/GNUmakefile.68k

@@ -334,6 +334,7 @@ C_LIB = \
 	stdlib_get_errno.o \
 	stdlib_get_slab_usage.o \
 	stdlib_get_slab_allocations.o \
+	stdlib_get_slab_stats.o \
 	stdlib_isresident.o \
 	stdlib_labs.o \
 	stdlib_llabs.o \
@@ -373,6 +374,7 @@ C_LIB = \
 	stdlib_showerror.o \
 	stdlib_slab.o \
 	stdlib_slab_max_size.o \
+	stdlib_slab_purge_threshold.o \
 	stdlib_srand.o \
 	stdlib_stacksize.o \
 	stdlib_stack_usage.o \
@@ -1124,25 +1126,29 @@ $(LIBC_OBJS)/stdlib_getdefstacksize.o : stdlib_getdefstacksize.c stdlib_gcc_help
 
 $(LIBC_OBJS)/stdlib_shell_escape.o : stdlib_shell_escape.c stdlib_gcc_help.h
 
-$(LIBC_OBJS)/stdlib_alloca.o : stdlib_alloca.c stdlib_memory.h
+$(LIBC_OBJS)/stdlib_alloca.o : stdlib_alloca.c stdlib_memory.h include/stdlib.h
 
-$(LIBC_OBJS)/stdlib_calloc.o : stdlib_calloc.c stdlib_memory.h
+$(LIBC_OBJS)/stdlib_calloc.o : stdlib_calloc.c stdlib_memory.h include/stdlib.h
 
-$(LIBC_OBJS)/stdlib_free.o : stdlib_free.c stdlib_memory.h
+$(LIBC_OBJS)/stdlib_free.o : stdlib_free.c stdlib_memory.h include/stdlib.h
 
-$(LIBC_OBJS)/stdlib_malloc.o : stdlib_malloc.c stdlib_memory.h
+$(LIBC_OBJS)/stdlib_malloc.o : stdlib_malloc.c stdlib_memory.h include/stdlib.h
 
-$(LIBC_OBJS)/stdlib_slab.o : stdlib_slab.c stdlib_memory.h
+$(LIBC_OBJS)/stdlib_slab.o : stdlib_slab.c stdlib_memory.h include/stdlib.h
 
-$(LIBC_OBJS)/stdlib_free_unused_slabs.o : stdlib_free_unused_slabs.c stdlib_memory.h
+$(LIBC_OBJS)/stdlib_slab_purge_threshold.o : stdlib_slab_purge_threshold.c stdlib_memory.h include/stdlib.h
 
-$(LIBC_OBJS)/stdlib_get_slab_usage.o : stdlib_get_slab_usage.c stdlib_memory.h
+$(LIBC_OBJS)/stdlib_get_slab_stats.o : stdlib_get_slab_stats.c stdlib_memory.h include/stdlib.h
 
-$(LIBC_OBJS)/stdlib_get_slab_allocations.o : stdlib_get_slab_allocations.c stdlib_memory.h
+$(LIBC_OBJS)/stdlib_free_unused_slabs.o : stdlib_free_unused_slabs.c stdlib_memory.h include/stdlib.h
 
-$(LIBC_OBJS)/stdlib_realloc.o : stdlib_realloc.c stdlib_memory.h
+$(LIBC_OBJS)/stdlib_get_slab_usage.o : stdlib_get_slab_usage.c stdlib_memory.h include/stdlib.h
 
-$(LIBC_OBJS)/stdlib_red_black.o : stdlib_red_black.c stdlib_memory.h
+$(LIBC_OBJS)/stdlib_get_slab_allocations.o : stdlib_get_slab_allocations.c stdlib_memory.h include/stdlib.h
+
+$(LIBC_OBJS)/stdlib_realloc.o : stdlib_realloc.c stdlib_memory.h include/stdlib.h
+
+$(LIBC_OBJS)/stdlib_red_black.o : stdlib_red_black.c stdlib_memory.h include/stdlib.h
 
 ##############################################################################
 

library/amiga.lib_rev.h

@@ -1,6 +1,6 @@
 #define VERSION		1
-#define REVISION	211
-#define DATE		"23.11.2016"
-#define VERS		"amiga.lib 1.211"
-#define VSTRING		"amiga.lib 1.211 (23.11.2016)\r\n"
-#define VERSTAG		"\0$VER: amiga.lib 1.211 (23.11.2016)"
+#define REVISION	212
+#define DATE		"27.11.2016"
+#define VERS		"amiga.lib 1.212"
+#define VSTRING		"amiga.lib 1.212 (27.11.2016)\r\n"
+#define VERSTAG		"\0$VER: amiga.lib 1.212 (27.11.2016)"

library/amiga.lib_rev.rev

@@ -1 +1 @@
-211
+212

library/c.lib_rev.h

@@ -1,6 +1,6 @@
 #define VERSION		1
-#define REVISION	211
-#define DATE		"23.11.2016"
-#define VERS		"c.lib 1.211"
-#define VSTRING		"c.lib 1.211 (23.11.2016)\r\n"
-#define VERSTAG		"\0$VER: c.lib 1.211 (23.11.2016)"
+#define REVISION	212
+#define DATE		"27.11.2016"
+#define VERS		"c.lib 1.212"
+#define VSTRING		"c.lib 1.212 (27.11.2016)\r\n"
+#define VERSTAG		"\0$VER: c.lib 1.212 (27.11.2016)"

library/c.lib_rev.rev

@@ -1 +1 @@
-211
+212

library/changes

@@ -1,3 +1,15 @@
+c.lib 1.212 (27.11.2016)
+
+- Unused slabs which get recycled are no longer reinitialized from
+  scratch if their chunk size matches what the allocator needed.
+  If the chunk size matches, the list of available chunks is
+  left unchanged, and just the various counters are reset.
+
+- Added __get_slab_stats() function.
+
+- Added support for global __slab_purge_threshold tuning variable.
+
+
 c.lib 1.211 (23.11.2016)
 
 - Added more consistency checking to the slab allocator, which is

library/debug.lib_rev.h

@@ -1,6 +1,6 @@
 #define VERSION		1
-#define REVISION	211
-#define DATE		"23.11.2016"
-#define VERS		"debug.lib 1.211"
-#define VSTRING		"debug.lib 1.211 (23.11.2016)\r\n"
-#define VERSTAG		"\0$VER: debug.lib 1.211 (23.11.2016)"
+#define REVISION	212
+#define DATE		"27.11.2016"
+#define VERS		"debug.lib 1.212"
+#define VSTRING		"debug.lib 1.212 (27.11.2016)\r\n"
+#define VERSTAG		"\0$VER: debug.lib 1.212 (27.11.2016)"

library/debug.lib_rev.rev

@@ -1 +1 @@
-211
+212

library/include/stdlib.h

@@ -173,6 +173,19 @@ extern int rand_r(unsigned int * seed);
 
 extern unsigned long __slab_max_size;
 
+/*
+ * The slab allocator will periodically free all currently unused memory.
+ * You can control how much memory should be released, instead of
+ * releasing everything.
+ *
+ * This would make the slab allocator release only up to 512 KBytes of
+ * unused memory at a time:
+ *
+ * unsigned long __slab_purge_threshold = 512 * 1024;
+ */
+
+extern unsigned long __slab_purge_threshold;
+
 /****************************************************************************/
 
 /*
@@ -250,6 +263,11 @@ struct __slab_usage_information
 
 	/* How many memory chunks in this slab are being used? */
 	size_t	sui_num_chunks_used;
+
+	/* How many time was this slab reused without reinitializing
+	 * it all over again from scratch?
+	 */
+	size_t	sui_num_reused;
 };
 
 /****************************************************************************/
@@ -324,6 +342,31 @@ void __get_slab_allocations(__slab_allocation_callback callback);
 
 /****************************************************************************/
 
+/*
+ * You can obtain information about the memory managed by the slab allocator,
+ * as well as additional information about the slab allocator's performance
+ * in JSON format. This format can be used for more detailed analysis.
+ *
+ * You supply a function which will be called for each line of the JSON
+ * data produced. You can store this data in a file, or in the clipboard,
+ * for later use. Your function must return 0 if it wants to be called
+ * again, or return -1 if it wants to stop (e.g. if an error occured
+ * when writing the JSON data to disk). The same "user_data" pointer which
+ * you pass to __get_slab_stats() will be passed to your callback function.
+ *
+ * Please note that this function works within the context of the memory
+ * allocation system and is not safe to call from interrupt code. It may
+ * break a Forbid() or Disable() condition.
+ */
+
+typedef int (* __slab_status_callback)(void * user_data, const char * line, size_t line_length);
+
+/****************************************************************************/
+
+extern void __get_slab_stats(void * user_data, __slab_status_callback callback);
+
+/****************************************************************************/
+
 /*
  * You can request to use the alloca() variant that actually does allocate
  * memory from the system rather than the current stack frame, which will

library/libc.gmk

@@ -220,6 +220,7 @@ C_LIB := \
 	stdlib_get_errno.o \
 	stdlib_get_slab_usage.o \
 	stdlib_get_slab_allocations.o \
+	stdlib_get_slab_stats.o \
 	stdlib_isresident.o \
 	stdlib_labs.o \
 	stdlib_llabs.o \
@@ -260,6 +261,7 @@ C_LIB := \
 	stdlib_showerror.o \
 	stdlib_slab.o \
 	stdlib_slab_max_size.o \
+	stdlib_slab_purge_threshold.o \
 	stdlib_srand.o \
 	stdlib_stacksize.o \
 	stdlib_stack_usage.o \

library/m.lib_rev.h

@@ -1,6 +1,6 @@
 #define VERSION		1
-#define REVISION	211
-#define DATE		"23.11.2016"
-#define VERS		"m.lib 1.211"
-#define VSTRING		"m.lib 1.211 (23.11.2016)\r\n"
-#define VERSTAG		"\0$VER: m.lib 1.211 (23.11.2016)"
+#define REVISION	212
+#define DATE		"27.11.2016"
+#define VERS		"m.lib 1.212"
+#define VSTRING		"m.lib 1.212 (27.11.2016)\r\n"
+#define VERSTAG		"\0$VER: m.lib 1.212 (27.11.2016)"

library/m.lib_rev.rev

@@ -1 +1 @@
-211
+212

library/m881.lib_rev.h

@@ -1,6 +1,6 @@
 #define VERSION		1
-#define REVISION	211
-#define DATE		"23.11.2016"
-#define VERS		"m881.lib 1.211"
-#define VSTRING		"m881.lib 1.211 (23.11.2016)\r\n"
-#define VERSTAG		"\0$VER: m881.lib 1.211 (23.11.2016)"
+#define REVISION	212
+#define DATE		"27.11.2016"
+#define VERS		"m881.lib 1.212"
+#define VSTRING		"m881.lib 1.212 (27.11.2016)\r\n"
+#define VERSTAG		"\0$VER: m881.lib 1.212 (27.11.2016)"

library/m881.lib_rev.rev

@@ -1 +1 @@
-211
+212

library/net.lib_rev.h

@@ -1,6 +1,6 @@
 #define VERSION		1
-#define REVISION	211
-#define DATE		"23.11.2016"
-#define VERS		"net.lib 1.211"
-#define VSTRING		"net.lib 1.211 (23.11.2016)\r\n"
-#define VERSTAG		"\0$VER: net.lib 1.211 (23.11.2016)"
+#define REVISION	212
+#define DATE		"27.11.2016"
+#define VERS		"net.lib 1.212"
+#define VSTRING		"net.lib 1.212 (27.11.2016)\r\n"
+#define VERSTAG		"\0$VER: net.lib 1.212 (27.11.2016)"

library/net.lib_rev.rev

@@ -1 +1 @@
-211
+212

library/smakefile

@@ -521,6 +521,7 @@ STDLIB_OBJ = \
 	stdlib_get_errno.o \
 	stdlib_get_slab_usage.o \
 	stdlib_get_slab_allocations.o \
+	stdlib_get_slab_stats.o \
 	stdlib_isresident.o \
 	stdlib_labs.o \
 	stdlib_ldiv.o \
@@ -552,6 +553,7 @@ STDLIB_OBJ = \
 	stdlib_showerror.o \
 	stdlib_slab.o \
 	stdlib_slab_max_size.o \
+	stdlib_slab_purge_threshold.o \
 	stdlib_srand.o \
 	stdlib_arg.o \
 	stdlib_stack_usage.o \
@@ -804,6 +806,10 @@ stdlib_slab.o : stdlib_slab.c stdlib_memory.h
 
 stdlib_free_unused_slabs.o : stdlib_free_unused_slabs.c stdlib_memory.h
 
+stdlib_slab_max_size.o : stdlib_slab_max_size.c stdlib_memory.h
+
+stdlib_slab_purge_threshold.o : stdlib_slab_purge_threshold.o stdlib_memory.h
+
 stdlib_get_slab_usage.o : stdlib_get_slab_usage.c stdlib_memory.h
 
 stdlib_realloc.o : stdlib_realloc.c stdlib_memory.h

library/stdlib_get_slab_stats.c

@@ -0,0 +1,200 @@
+/*
+ * :ts=4
+ *
+ * Portable ISO 'C' (1994) runtime library for the Amiga computer
+ * Copyright (c) 2002-2015 by Olaf Barthel <obarthel (at) gmx.net>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   - Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *
+ *   - Neither the name of Olaf Barthel nor the names of contributors
+ *     may be used to endorse or promote products derived from this
+ *     software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _STDLIB_HEADERS_H
+#include "stdlib_headers.h"
+#endif /* _STDLIB_HEADERS_H */
+
+/****************************************************************************/
+
+#ifndef _STDLIB_MEMORY_H
+#include "stdlib_memory.h"
+#endif /* _STDLIB_MEMORY_H */
+
+/****************************************************************************/
+
+struct context
+{
+	int						status;
+	void *					user_data;
+	__slab_status_callback	callback;
+	char *					buffer;
+	size_t					buffer_size;
+};
+
+/****************************************************************************/
+
+static void print(struct context * ct, const char * format, ...)
+{
+	if(ct->status == 0)
+	{
+		va_list args;
+		int len;
+
+		va_start(args,format);
+		len = vsnprintf(ct->buffer, ct->buffer_size, format, args);
+		va_end(args);
+
+		/* This shouldn't happen: the buffer ought to be large enough
+		 * to hold every single line.
+		 */
+		if(len >= (int)ct->buffer_size)
+			len = strlen(ct->buffer);
+
+		ct->status = (*ct->callback)(ct->user_data, ct->buffer, len);
+	}
+}
+
+/****************************************************************************/
+
+void
+__get_slab_stats(void * user_data, __slab_status_callback callback)
+{
+	if(__slab_data.sd_InUse)
+	{
+		static int times_checked = 1;
+
+		const struct SlabNode * sn;
+		size_t num_empty_slabs = 0;
+		size_t num_full_slabs = 0;
+		size_t num_slabs = 0;
+		size_t slab_allocation_size = 0;
+		size_t total_slab_allocation_size = 0;
+		struct context ct;
+		char line[1024];
+		char time_buffer[40];
+		time_t now;
+		struct tm when;
+		int i;
+
+ 		memset(&ct, 0, sizeof(ct));
+
+		ct.user_data	= user_data;
+		ct.callback		= callback;
+		ct.buffer		= line;
+		ct.buffer_size	= sizeof(line);
+
+		__memory_lock();
+
+		now = time(NULL);
+		localtime_r(&now, &when);
+
+		strftime(time_buffer, sizeof(time_buffer), "%Y-%m-%dT%H:%M:%S", &when);
+
+		print(&ct,"{\n");
+
+		print(&ct,"\t\"when\": \"%s\",\n", time_buffer);
+		print(&ct,"\t\"times_checked\": %d,\n", times_checked++);
+		print(&ct,"\t\"slab_size\": %zu,\n", __slab_data.sd_StandardSlabSize);
+		print(&ct,"\t\"num_single_allocations\": %zu,\n", __slab_data.sd_NumSingleAllocations);
+		print(&ct,"\t\"total_single_allocation_size\": %zu,\n", __slab_data.sd_TotalSingleAllocationSize);
+
+		if(__slab_data.sd_SingleAllocations.mlh_Head->mln_Succ != NULL)
+		{
+			const struct SlabSingleAllocation * ssa;
+
+			print(&ct,"\t\"single_allocations\": [\n");
+
+			for(ssa = (struct SlabSingleAllocation *)__slab_data.sd_SingleAllocations.mlh_Head ;
+			    ssa->ssa_MinNode.mln_Succ != NULL && ct.status == 0 ;
+			    ssa = (struct SlabSingleAllocation *)ssa->ssa_MinNode.mln_Succ)
+			{
+				print(&ct,"\t\t{ \"size\": %lu, \"total_size\": %lu }%s\n",
+					ssa->ssa_Size - sizeof(*ssa), ssa->ssa_Size,
+					ssa->ssa_MinNode.mln_Succ->mln_Succ != NULL ? "," : "");
+			}
+
+			print(&ct,"\t],\n");
+		}
+		else
+		{
+			print(&ct,"\t\"single_allocations\": [],\n");
+		}
+
+		for(i = 0 ; i < (int)NUM_ENTRIES(__slab_data.sd_Slabs) ; i++)
+		{
+			for(sn = (struct SlabNode *)__slab_data.sd_Slabs[i].mlh_Head ;
+			    sn->sn_MinNode.mln_Succ != NULL ;
+			    sn = (struct SlabNode *)sn->sn_MinNode.mln_Succ)
+			{
+				if (sn->sn_UseCount == 0)
+					num_empty_slabs++;
+				else if (sn->sn_UseCount == sn->sn_Count)
+					num_full_slabs++;
+
+				num_slabs++;
+
+				slab_allocation_size += sn->sn_ChunkSize * sn->sn_UseCount;
+				total_slab_allocation_size += sizeof(*sn) + __slab_data.sd_StandardSlabSize;
+			}
+		}
+
+		print(&ct,"\t\"num_slabs\": %zu,\n", num_slabs);
+		print(&ct,"\t\"num_empty_slabs\": %zu,\n", num_empty_slabs);
+		print(&ct,"\t\"num_full_slabs\": %zu,\n", num_full_slabs);
+		print(&ct,"\t\"slab_allocation_size\": %zu,\n", slab_allocation_size);
+		print(&ct,"\t\"total_slab_allocation_size\": %zu,\n", total_slab_allocation_size);
+
+		if(num_slabs > 0)
+		{
+			const char * eol = "";
+
+			print(&ct,"\t\"slabs\": [\n");
+
+			for(i = 0 ; i < (int)NUM_ENTRIES(__slab_data.sd_Slabs) && ct.status == 0 ; i++)
+			{
+				for(sn = (struct SlabNode *)__slab_data.sd_Slabs[i].mlh_Head ;
+				    sn->sn_MinNode.mln_Succ != NULL && ct.status == 0 ;
+				    sn = (struct SlabNode *)sn->sn_MinNode.mln_Succ)
+				{
+					print(&ct,"%s\t\t{ \"size\": %lu, \"chunks\": %lu, \"chunks_in_use\": %lu, \"times_reused\": %lu }",
+						eol,
+						sn->sn_ChunkSize,
+						sn->sn_Count,
+						sn->sn_UseCount,
+						sn->sn_NumReused);
+
+					eol = ",\n";
+				}
+			}
+
+			print(&ct,"\n\t]\n");
+		}
+		else
+		{
+			print(&ct,"\t\"slabs\": []\n");
+		}
+
+		print(&ct,"}\n");
+
+		__memory_unlock();
+	}
+}

library/stdlib_get_slab_usage.c

@@ -87,6 +87,7 @@ __get_slab_usage(__slab_usage_callback callback)
 					sui.sui_chunk_size		= sn->sn_ChunkSize;
 					sui.sui_num_chunks		= sn->sn_Count;
 					sui.sui_num_chunks_used	= sn->sn_UseCount;
+					sui.sui_num_reused		= sn->sn_NumReused;
 
 					sui.sui_slab_index++;
 

library/stdlib_malloc.c

@@ -503,7 +503,7 @@ STDLIB_CONSTRUCTOR(stdlib_memory_init)
 	#if defined(__USE_SLAB_ALLOCATOR)
 	{
 		/* ZZZ this is just for the purpose of testing */
-		#if 0
+		#if 1
 		{
 			TEXT slab_size_var[20];
 

library/stdlib_memory.h

@@ -235,6 +235,11 @@ struct SlabNode
 	/* How many chunks of this slab are currently in use? */
 	ULONG			sn_UseCount;
 
+	/* How many times was this slab reused instead of allocating
+	 * it from system memory?
+	 */
+	ULONG			sn_NumReused;
+
 	/* This contains all the chunks of memory which are available
 	 * for allocation.
 	 */
@@ -286,7 +291,7 @@ struct SlabData
 	 */
 	size_t			sd_StandardSlabSize;
 
-	/* These fields kees track of how many entries there are in
+	/* These fields keep track of how many entries there are in
 	 * the sd_SingleAllocations list, and how much memory these
 	 * allocations occupy.
 	 */
@@ -303,6 +308,7 @@ struct SlabData
 
 extern struct SlabData NOCOMMON	__slab_data;
 extern unsigned long NOCOMMON	__slab_max_size;
+extern unsigned long NOCOMMON	__slab_purge_threshold;
 
 /****************************************************************************/
 

library/stdlib_realloc.c

@@ -31,6 +31,8 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
+/*#define DEBUG*/
+
 #ifndef _STDLIB_HEADERS_H
 #include "stdlib_headers.h"
 #endif /* _STDLIB_HEADERS_H */
@@ -76,6 +78,7 @@ __realloc(void *ptr,size_t size,const char * file,int line)
 #endif /* UNIX_PATH_SEMANTICS */
 	else
 	{
+		size_t old_size;
 		struct MemoryNode * mn;
 		BOOL reallocate;
 
@@ -108,29 +111,23 @@ __realloc(void *ptr,size_t size,const char * file,int line)
 		}
 		#endif /* __MEM_DEBUG */
 
-		if(mn == NULL || mn->mn_NeverFree)
+		if(mn == NULL || FLAG_IS_SET(mn->mn_Size, MN_SIZE_NEVERFREE))
 		{
 			SHOWMSG("cannot free this chunk");
 			goto out;
 		}
 
+		old_size = GET_MN_SIZE(mn);
+
 		/* Don't do anything unless the size of the allocation
 		   has really changed. */
 		#if defined(__MEM_DEBUG)
 		{
-			reallocate = (mn->mn_Size != size);
+			reallocate = (old_size != size);
 		}
 		#else
 		{
-			size_t rounded_allocation_size;
-
-			/* Round the total allocation size to the operating system
-			   granularity. */
-			rounded_allocation_size = __get_allocation_size(size);
-
-			assert( rounded_allocation_size >= size );
-
-			if(rounded_allocation_size > mn->mn_Size)
+			if(size > old_size)
 			{
 				/* Allocation size should grow. */
 				reallocate = TRUE;
@@ -143,7 +140,7 @@ __realloc(void *ptr,size_t size,const char * file,int line)
 				                 allocation. We also take into account that the
 				                 actual size of the allocation is affected by a
 				                 certain operating system imposed granularity. */
-				reallocate = (rounded_allocation_size < mn->mn_Size && rounded_allocation_size <= mn->mn_Size / 2);
+				reallocate = (size < old_size && size <= old_size / 2);
 			}
 		}
 		#endif /* __MEM_DEBUG */
@@ -152,7 +149,7 @@ __realloc(void *ptr,size_t size,const char * file,int line)
 		{
 			void * new_ptr;
 
-			D(("realloc() size has changed; old=%ld, new=%ld",mn->mn_Size,size));
+			D(("realloc() size has changed; old=%ld, new=%ld",old_size,size));
 
 			/* We allocate the new memory chunk before we
 			   attempt to replace the old. */
@@ -164,8 +161,8 @@ __realloc(void *ptr,size_t size,const char * file,int line)
 			}
 
 			/* Copy the contents of the old allocation to the new buffer. */
-			if(size > mn->mn_Size)
-				size = mn->mn_Size;
+			if(size > old_size)
+				size = old_size;
 
 			memmove(new_ptr,ptr,size);
 
@@ -177,7 +174,7 @@ __realloc(void *ptr,size_t size,const char * file,int line)
 		}
 		else
 		{
-			D(("size didn't actually change that much (%ld -> %ld); returning memory block as is.",mn->mn_Size,size));
+			D(("size didn't actually change that much (%ld -> %ld); returning memory block as is.",old_size,size));
 
 			/* No change in size. */
 			result = ptr;

library/stdlib_slab.c

@@ -125,6 +125,7 @@ __slab_allocate(size_t allocation_size)
 	else
 	{
 		struct MinList * slab_list = NULL;
+		BOOL slab_reused = FALSE;
 		ULONG entry_size;
 		ULONG chunk_size;
 		int slab_index;
@@ -252,11 +253,22 @@ __slab_allocate(size_t allocation_size)
 						/* Unlink from list of empty slabs. */
 						Remove((struct Node *)free_node);
 
+						/* If the chunk size of the reused slab matches
+						 * exactly what we need then we won't have to
+						 * completely reinitialize it again.
+						 */
+						if(sn->sn_ChunkSize == chunk_size)
+						{
+							slab_reused = TRUE;
+						}
+						else
+						{
 							/* Unlink from list of slabs which keep chunks
 							 * of the same size. It will be added there
 							 * again, at a different position.
 							 */
 							Remove((struct Node *)sn);
+						}
 
 						D(("reusing a slab"));
 
@@ -295,19 +307,28 @@ __slab_allocate(size_t allocation_size)
 
 				if(new_sn != NULL)
 				{
-					struct MinNode * free_chunk;
-					ULONG num_free_chunks = 0;
-					BYTE * first_byte;
-					BYTE * last_byte;
-
 					D(("setting up slab 0x%08lx", new_sn));
 
 					assert( chunk_size <= __slab_data.sd_StandardSlabSize );
 
+					/* Do we have to completely initialize this slab from scratch? */
+					if(NOT slab_reused)
+					{
+						struct SlabChunk * free_chunk;
+						ULONG num_free_chunks = 0;
+						BYTE * first_byte;
+						BYTE * last_byte;
+
 						memset(new_sn,0,sizeof(*new_sn));
 
 						NewList((struct List *)&new_sn->sn_FreeList);
 
+						/* This slab has room for new allocations, so make sure that
+						 * it goes to the front of the slab list. It will be used
+						 * by the next allocation request of this size.
+						 */
+						AddHead((struct List *)slab_list,(struct Node *)new_sn);
+
 						/* Split up the slab memory into individual chunks
 						 * of the same size and keep track of them
 						 * in the free list. The memory managed by
@@ -317,37 +338,44 @@ __slab_allocate(size_t allocation_size)
 						first_byte	= (BYTE *)&new_sn[1];
 						last_byte	= &first_byte[__slab_data.sd_StandardSlabSize - chunk_size];
 
-					for(free_chunk = (struct MinNode *)first_byte ;
-					    free_chunk <= (struct MinNode *)last_byte;
-					    free_chunk = (struct MinNode *)(((BYTE *)free_chunk) + chunk_size))
+						for(free_chunk = (struct SlabChunk *)first_byte ;
+						    free_chunk <= (struct SlabChunk *)last_byte;
+						    free_chunk = (struct SlabChunk *)(((BYTE *)free_chunk) + chunk_size))
 						{
 							AddTail((struct List *)&new_sn->sn_FreeList, (struct Node *)free_chunk);
 							num_free_chunks++;
 						}
 
-					D(("slab contains %lu chunks, %lu bytes each",num_free_chunks,chunk_size));
+						new_sn->sn_Count		= num_free_chunks;
+						new_sn->sn_ChunkSize	= chunk_size;
+
+						D(("new slab contains %lu chunks, %lu bytes each",num_free_chunks,chunk_size));
+					}
+					/* This slab was reused and need not be reinitialized from scratch. */
+					else
+					{
+						new_sn->sn_NumReused++;
+
+						assert( new_sn->sn_FreeList.mlh_Head != NULL );
+						assert( new_sn->sn_ChunkSize == chunk_size );
+						assert( new_sn->sn_Count == 0 );
+					}
 
 					/* Grab the first free chunk (there has to be one). */
 					chunk = (struct SlabChunk *)RemHead((struct List *)&new_sn->sn_FreeList);
 
-					assert( chunk != NULL );
-
 					/* Keep track of this chunk's parent slab. */
 					chunk->sc_Parent = new_sn;
 
+					assert( chunk != NULL );
+					assert( chunk->sc_Parent == new_sn );
+
 					allocation = &chunk[1];
 
-					D(("allocation succeeded at 0x%08lx in slab 0x%08lx (slab use count = %lu)",allocation,new_sn,new_sn->sn_UseCount+1));
-
-					/* Set up the new slab and put it where it belongs. */
-					new_sn->sn_EmptyDecay	= 0;
+					/* This slab is now in use. */
 					new_sn->sn_UseCount = 1;
-					new_sn->sn_Count		= num_free_chunks;
-					new_sn->sn_ChunkSize	= chunk_size;
 
-					SHOWVALUE(new_sn->sn_ChunkSize);
-
-					AddHead((struct List *)slab_list,(struct Node *)new_sn);
+					D(("allocation succeeded at 0x%08lx in slab 0x%08lx (slab use count = %lu)",allocation,new_sn,new_sn->sn_UseCount));
 				}
 
 				/* Mark unused slabs for purging, and purge those which
@@ -355,6 +383,8 @@ __slab_allocate(size_t allocation_size)
 				 */
 				if(purge)
 				{
+					size_t total_purged = 0;
+
 					D(("purging empty slabs"));
 
 					for(free_node = (struct MinNode *)__slab_data.sd_EmptySlabs.mlh_Head ; 
@@ -380,6 +410,15 @@ __slab_allocate(size_t allocation_size)
 							Remove((struct Node *)sn);
 
 							FreeVec(sn);
+
+							total_purged += sizeof(*sn) + __slab_data.sd_StandardSlabSize;
+
+							/* Stop releasing memory if we reach the threshold. If no
+							 * threshold has been set, we will free as much memory
+							 * as possible.
+							 */
+							if(__slab_purge_threshold > 0 && total_purged >= __slab_purge_threshold)
+								break;
 						}
 						/* Give it another chance. */
 						else
@@ -700,6 +739,21 @@ __slab_init(size_t slab_size)
 
 /****************************************************************************/
 
+#if DEBUG
+
+static int print_json(void * ignore,const char * buffer,size_t len)
+{
+	extern void kputs(const char * str);
+
+	kputs(buffer);
+
+	return(0);
+}
+
+#endif /* DEBUG */
+
+/****************************************************************************/
+
 void
 __slab_exit(void)
 {
@@ -712,7 +766,19 @@ __slab_exit(void)
 		struct SlabNode * sn_next;
 		struct MinNode * mn;
 		struct MinNode * mn_next;
-		int i;
+		size_t slab_count = 0, total_slab_size = 0;
+		size_t single_allocation_count = 0, total_single_allocation_size = 0;
+		int i, j;
+
+		#if DEBUG
+		{
+			kprintf("---BEGIN JSON DATA ---\n");
+
+			__get_slab_stats(NULL, print_json);
+
+			kprintf("---END JSON DATA ---\n\n");
+		}
+		#endif /* DEBUG */
 
 		D(("freeing slabs"));
 
@@ -720,25 +786,38 @@ __slab_exit(void)
 		for(i = 0 ; i < (int)NUM_ENTRIES(__slab_data.sd_Slabs) ; i++)
 		{
 			if(__slab_data.sd_Slabs[i].mlh_Head->mln_Succ != NULL)
-				D(("freeing slab #%ld (%lu bytes per chunk)", i, (1UL << i)));
+				D(("freeing slab slot #%ld (%lu bytes per chunk)", i, (1UL << i)));
 
-			for(sn = (struct SlabNode *)__slab_data.sd_Slabs[i].mlh_Head ;
+			for(sn = (struct SlabNode *)__slab_data.sd_Slabs[i].mlh_Head, j = 0 ;
 			    sn->sn_MinNode.mln_Succ != NULL ;
 			    sn = sn_next)
 			{
 				sn_next = (struct SlabNode *)sn->sn_MinNode.mln_Succ;
 
+				D((" slab #%ld.%ld at 0x%08lx",i, ++j, sn));
+				D(("  fragmentation = %ld%%",100 * (__slab_data.sd_StandardSlabSize - sn->sn_Count * sn->sn_ChunkSize) / __slab_data.sd_StandardSlabSize));
+				D(("  total space used = %ld (%ld%%)",sn->sn_UseCount * sn->sn_ChunkSize, 100 * sn->sn_UseCount / sn->sn_Count));
+				D(("  number of chunks total = %ld",sn->sn_Count));
+				D(("  number of chunks used = %ld%s",sn->sn_UseCount,sn->sn_UseCount == 0 ? " (empty)" : (sn->sn_UseCount == sn->sn_Count) ? " (full)" : ""));
+				D(("  how often reused = %ld",sn->sn_NumReused));
+
+				total_slab_size += sizeof(*sn) + __slab_data.sd_StandardSlabSize;
+				slab_count++;
+
 				FreeVec(sn);
 			}
 		}
 
+		if(slab_count > 0)
+			D(("number of slabs = %ld, total slab size = %ld bytes",slab_count, total_slab_size));
+
 		if(__slab_data.sd_SingleAllocations.mlh_Head->mln_Succ != NULL)
 			D(("freeing single allocations"));
 
 		/* Free the memory allocated for each allocation which did not
 		 * go into a slab.
 		 */
-		for(mn = __slab_data.sd_SingleAllocations.mlh_Head ;
+		for(mn = __slab_data.sd_SingleAllocations.mlh_Head, j = 0 ;
 		    mn->mln_Succ != NULL ;
 		    mn = mn_next)
 		{
@@ -746,9 +825,17 @@ __slab_exit(void)
 
 			ssa = (struct SlabSingleAllocation *)mn;
 
+			D((" allocation #%ld at 0x%08lx, %lu bytes", ++j, ssa, ssa->ssa_Size));
+
+			total_single_allocation_size += ssa->ssa_Size;
+			single_allocation_count++;
+
 			FreeMem(ssa, ssa->ssa_Size);
 		}
 
+		if(single_allocation_count > 0)
+			D(("number of single allocations = %ld, total single allocation size = %ld", single_allocation_count, total_single_allocation_size));
+
 		__slab_data.sd_InUse = FALSE;
 	}
 

library/stdlib_slab_purge_threshold.c

@@ -0,0 +1,38 @@
+/*
+ * :ts=4
+ *
+ * Portable ISO 'C' (1994) runtime library for the Amiga computer
+ * Copyright (c) 2002-2015 by Olaf Barthel <obarthel (at) gmx.net>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   - Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *
+ *   - Neither the name of Olaf Barthel nor the names of contributors
+ *     may be used to endorse or promote products derived from this
+ *     software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _STDLIB_HEADERS_H
+#include "stdlib_headers.h"
+#endif /* _STDLIB_HEADERS_H */
+
+/****************************************************************************/
+
+unsigned long __slab_purge_threshold;

library/unix.lib_rev.h

@@ -1,6 +1,6 @@
 #define VERSION		1
-#define REVISION	211
-#define DATE		"23.11.2016"
-#define VERS		"unix.lib 1.211"
-#define VSTRING		"unix.lib 1.211 (23.11.2016)\r\n"
-#define VERSTAG		"\0$VER: unix.lib 1.211 (23.11.2016)"
+#define REVISION	212
+#define DATE		"27.11.2016"
+#define VERS		"unix.lib 1.212"
+#define VSTRING		"unix.lib 1.212 (27.11.2016)\r\n"
+#define VERSTAG		"\0$VER: unix.lib 1.212 (27.11.2016)"

library/unix.lib_rev.rev

@@ -1 +1 @@
-211
+212

test_programs/GNUmakefile.68k

@@ -13,7 +13,7 @@ DELETE = delete all quiet
 
 .c.o:
 	@echo "Compiling $<"
-	@$(CC) -c $(CFLAGS) $<
+	$(CC) -c $(CFLAGS) $<
 
 ##############################################################################
 
@@ -31,7 +31,7 @@ WARNINGS = \
 
 INCLUDE = -I../library/include
 LIB = -L../library/lib
- OPTIONS = -DNDEBUG -fno-builtin -fwritable-strings -DNO_INLINE_STDARG -DIEEE_FLOATING_POINT_SUPPORT -DVERBOSE
+ OPTIONS = -DNDEBUG -fno-builtin -fwritable-strings -DNO_INLINE_STDARG -DIEEE_FLOATING_POINT_SUPPORT -DVERBOSE=1
 #OPTIONS = -D__MEM_DEBUG -fno-builtin
 #OPTIONS = -DDEBUG -D__MEM_DEBUG -DNO_INLINE_STDARG -fno-builtin
  OPTIMIZE = -O
@@ -50,14 +50,14 @@ all: test fgets_test iotest sscanf_test printf_test sprintf_test \
 	stack_size_test translate_test strtok_test uname simple \
 	fstat_stdout_test simple_sprintf date_test sscanf_64 factorial \
 	execvp_test setlocale rand fstat_test base_dir_nametest \
-	malloc-test
+	malloc-test slab-test
 
 clean:
 	$(DELETE) #?.o #?.map test fgets_test iotest sscanf_test printf_test \
 		sprintf_test stack_size_test translate_test strtok_test uname \
 		simple fstat_stdout_test fstat_test simple_sprintf date_test sscanf_64 \
 		factorial execvp_test setlocale rand base_dir_nametest \
-		malloc-test
+		malloc-test slab-test
 
 ##############################################################################
 
@@ -145,9 +145,13 @@ rand : rand.o
 	@echo "Linking $@"
 	$(CC) $(CFLAGS) -o $@ rand.o $(LIBS) -Wl,--cref,-M,-Map=$@.map
 
-malloc-test: malloc-test.o
+malloc-test : malloc-test.o
 	@echo "Linking $@"
-	$(CC) $(CFLAGS) -o $@ rand.o $(LIBS) -Wl,--cref,-M,-Map=$@.map
+	$(CC) $(CFLAGS) -o $@ malloc-test.o $(LIBS) -Wl,--cref,-M,-Map=$@.map
+
+slab-test : slab-test.o
+	@echo "Linking $@"
+	$(CC) $(CFLAGS) -o $@ slab-test.o $(LIBS) -Wl,--cref,-M,-Map=$@.map
 
 ##############################################################################
 

test_programs/slab-test.c

@@ -0,0 +1,26 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+unsigned long __slab_max_size = 4096;
+
+static int print_json(void * ignore,const char * buffer,size_t len)
+{
+	fputs(buffer, stdout);
+
+	return(0);
+}
+
+int
+main(int argc,char ** argv)
+{
+	int i;
+
+	srand(1);
+
+	for(i = 0 ; i < 1000 ; i++)
+		malloc(1 + (rand() %  8192));
+
+	__get_slab_stats(NULL, print_json);
+
+	return(0);
+}