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* [Qemu-devel] [PATCH v3] Two-Level IOPort Lookup
@ 2009-04-13 14:11 Brian Wheeler
  2009-04-13 14:40 ` malc
  0 siblings, 1 reply; 3+ messages in thread
From: Brian Wheeler @ 2009-04-13 14:11 UTC (permalink / raw)
  To: qemu-devel

I've fixed a few things:
	* my pointer arithmetic was gross looking, so I fixed it
	* added an allocated page count for stats when debugging


On my platform (x86-64) the in-tree implementation allocates 3.5M for
the PC target.  With this implementation the PC target consumes 2K of
pointer table + 256K of malloc'd memory.

For the Alpha target, statically allocating all 24-bits worth of ioport
tables is about 1G of ram.  With this patch, it uses 32K for the pointer
table and 512K of malloc'd memory

Is there anything else I need to look at before this patch is worthy of
inclusion?



Signed-off-by: Brian Wheeler <bdwheele@indiana.edu>

Index: vl.c
===================================================================
--- vl.c	(revision 7097)
+++ vl.c	(working copy)
@@ -168,8 +168,8 @@
 //#define DEBUG_IOPORT
 //#define DEBUG_NET
 //#define DEBUG_SLIRP
+//#define DEBUG_IOPORT_FIND
 
-
 #ifdef DEBUG_IOPORT
 #  define LOG_IOPORT(...) qemu_log_mask(CPU_LOG_IOPORT, ## __VA_ARGS__)
 #else
@@ -184,14 +184,31 @@
 /* Max number of bluetooth switches on the commandline.  */
 #define MAX_BT_CMDLINE 10
 
-/* XXX: use a two level table to limit memory usage */
-#define MAX_IOPORTS 65536
-
 const char *bios_dir = CONFIG_QEMU_SHAREDIR;
 const char *bios_name = NULL;
-static void *ioport_opaque[MAX_IOPORTS];
-static IOPortReadFunc *ioport_read_table[3][MAX_IOPORTS];
-static IOPortWriteFunc *ioport_write_table[3][MAX_IOPORTS];
+
+struct ioport {
+    void *opaque;
+    IOPortReadFunc *read[3];
+    IOPortWriteFunc *write[3];
+    void *pad;
+};
+typedef struct ioport ioport_t;
+
+#ifdef TARGET_ALPHA
+#define IOPORT_MAXBITS 24
+#define IOPORT_PAGEBITS 12
+#else
+#define IOPORT_MAXBITS 16
+#define IOPORT_PAGEBITS 8
+#endif
+
+#define IOPORT_ENTRYMASK ((1<<IOPORT_PAGEBITS)-1)
+#define IOPORT_PAGEMASK ~IOPORT_ENTRYMASK
+#define MAX_IOPORTS (1<<IOPORT_MAXBITS)
+
+ioport_t *ioport_table[1<<(IOPORT_MAXBITS-IOPORT_PAGEBITS)];
+
 /* Note: drives_table[MAX_DRIVES] is a dummy block driver if none available
    to store the VM snapshots */
 DriveInfo drives_table[MAX_DRIVES+1];
@@ -288,30 +305,78 @@
 static IOPortReadFunc default_ioport_readb, default_ioport_readw, default_ioport_readl;
 static IOPortWriteFunc default_ioport_writeb, default_ioport_writew, default_ioport_writel;
 
+
+static ioport_t ioport_default_func = {
+    NULL,
+    {default_ioport_readb, default_ioport_readw, default_ioport_readl},
+    {default_ioport_writeb, default_ioport_writew, default_ioport_writel},
+    NULL
+};
+
+static inline ioport_t *ioport_find(uint32_t address, int allocate) 
+{
+    uint32_t page = (address & IOPORT_PAGEMASK) >> IOPORT_PAGEBITS;
+    uint32_t entry = address & IOPORT_ENTRYMASK;
+#ifdef DEBUG_IOPORT_FIND
+    static int page_count = 0;
+    if (address >= (1<<IOPORT_MAXBITS)) {
+	hw_error("Maximum port # for this architecture is %d.  "
+		 "Port %d requested.", (1<<IOPORT_MAXBITS)-1, address);
+    }
+#endif
+    if (ioport_table[page] == NULL) {
+	if (allocate) {
+	    ioport_table[page]=qemu_mallocz((1<<IOPORT_PAGEBITS) * 
+					    sizeof(ioport_t));
+#ifdef DEBUG_IOPORT_FIND
+	    printf("Initializing ioport page %d to: %p (0x%lx bytes)\n", 
+		   page, ioport_table[page], 
+		   (1<<IOPORT_PAGEBITS)*sizeof(ioport_t));
+	    page_count++;
+#endif
+	} else {
+	    return &ioport_default_func;
+	}
+    }
+    ioport_t *p=&(ioport_table[page][entry]);
+
+#ifdef DEBUG_IOPORT_FIND
+    if (allocate) {
+	printf("port find %d:  page=%d, address=%p, entry=%d, address=%p, "
+	       "offset=0x%lx\n", address, page, ioport_table[page], 
+	       entry, p, p-ioport_table[page]);
+	printf("  data: %p\n", p->opaque);
+	printf("  read: %p, %p, %p\n", p->read[0], p->read[1], p->read[2]);
+	printf(" write: %p, %p, %p\n", p->write[0], p->write[1], p->write[2]);
+	
+	printf("    --- %d pages allocated, %ld bytes used. ---   \n", 
+	       page_count, 
+	       page_count * (sizeof(ioport_t) * (1<<IOPORT_PAGEBITS)));
+    }
+#endif
+    return p;
+}
+
 static uint32_t ioport_read(int index, uint32_t address)
 {
-    static IOPortReadFunc *default_func[3] = {
-        default_ioport_readb,
-        default_ioport_readw,
-        default_ioport_readl
-    };
-    IOPortReadFunc *func = ioport_read_table[index][address];
-    if (!func)
-        func = default_func[index];
-    return func(ioport_opaque[address], address);
+    ioport_t *p = ioport_find(address, 0);
+    IOPortReadFunc *func = p->read[index];
+    void *opaque = p->opaque;
+    if (!func) {
+        func = ioport_default_func.read[index];
+    }
+    return func(opaque, address);
 }
 
 static void ioport_write(int index, uint32_t address, uint32_t data)
 {
-    static IOPortWriteFunc *default_func[3] = {
-        default_ioport_writeb,
-        default_ioport_writew,
-        default_ioport_writel
-    };
-    IOPortWriteFunc *func = ioport_write_table[index][address];
-    if (!func)
-        func = default_func[index];
-    func(ioport_opaque[address], address, data);
+    ioport_t *p = ioport_find(address, 0);
+    IOPortWriteFunc *func = p->write[index];
+    void *opaque = p->opaque;
+    if (!func) {
+        func = ioport_default_func.write[index];
+    }
+    func(opaque, address, data);
 }
 
 static uint32_t default_ioport_readb(void *opaque, uint32_t address)
@@ -378,10 +443,11 @@
         return -1;
     }
     for(i = start; i < start + length; i += size) {
-        ioport_read_table[bsize][i] = func;
-        if (ioport_opaque[i] != NULL && ioport_opaque[i] != opaque)
+	ioport_t *p = ioport_find(i, 1);
+        p->read[bsize] = func;
+        if (p->opaque != NULL && p->opaque != opaque)
             hw_error("register_ioport_read: invalid opaque");
-        ioport_opaque[i] = opaque;
+        p->opaque = opaque;
     }
     return 0;
 }
@@ -403,10 +469,11 @@
         return -1;
     }
     for(i = start; i < start + length; i += size) {
-        ioport_write_table[bsize][i] = func;
-        if (ioport_opaque[i] != NULL && ioport_opaque[i] != opaque)
+        ioport_t *p = ioport_find(i, 1);
+        p->write[bsize] = func;
+        if (p->opaque != NULL && p->opaque != opaque)
             hw_error("register_ioport_write: invalid opaque");
-        ioport_opaque[i] = opaque;
+        p->opaque = opaque;
     }
     return 0;
 }
@@ -416,15 +483,16 @@
     int i;
 
     for(i = start; i < start + length; i++) {
-        ioport_read_table[0][i] = default_ioport_readb;
-        ioport_read_table[1][i] = default_ioport_readw;
-        ioport_read_table[2][i] = default_ioport_readl;
+        ioport_t *p = ioport_find(i, 1);
+        p->read[0] = default_ioport_readb;
+        p->read[1] = default_ioport_readw;
+        p->read[2] = default_ioport_readl;
 
-        ioport_write_table[0][i] = default_ioport_writeb;
-        ioport_write_table[1][i] = default_ioport_writew;
-        ioport_write_table[2][i] = default_ioport_writel;
+        p->write[0] = default_ioport_writeb;
+        p->write[1] = default_ioport_writew;
+        p->write[2] = default_ioport_writel;
 
-        ioport_opaque[i] = NULL;
+        p->opaque = NULL;
     }
 }

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2009-04-13 14:57 UTC | newest]

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2009-04-13 14:11 [Qemu-devel] [PATCH v3] Two-Level IOPort Lookup Brian Wheeler
2009-04-13 14:40 ` malc
2009-04-13 14:57   ` Brian Wheeler

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