Changeset 5266

Timestamp:

05/28/08 09:26:11 (5 years ago)

Author:

khali

Message:

Cache the byte data reads. As we keep reading the same registers over
and over again in the detection functions, and SMBus can be slow,
caching results in a big performance boost. This closes ticket #2326.

Location:

lm-sensors/branches/lm-sensors-3.0.0

Files:

• CHANGES (modified) (1 diff)
• prog/detect/sensors-detect (modified) (7 diffs)

lm-sensors/branches/lm-sensors-3.0.0/CHANGES

@@ -6 +6 @@
                   Add SMSC EMC6D103 support
                   Improve MAX6657, MAX6658, MAX6659 detection
+                  Cache the byte data reads (#2326)
 
 3.0.2 (2008-05-18)

lm-sensors/branches/lm-sensors-3.0.0/prog/detect/sensors-detect

@@ -46 +46 @@
 #########################
 
+use constant NO_CACHE => 1;
 use vars qw(@pci_adapters @chip_ids $i2c_addresses_to_scan @superio_ids
-            @cpu_ids $revision);
+            @cpu_ids $revision @i2c_byte_cache);
 
 $revision = '$Revision$ ($Date$)';
@@ -2690 +2691 @@
 {
   my ($file, $addr) = @_;
+
+  # Reset register data cache
+  @i2c_byte_cache = ();
+
   $addr += 0; # Make sure it's a number not a string
   ioctl $file, IOCTL_I2C_SLAVE, $addr or return 0;
@@ -2744 +2749 @@
 # $_[1]: Command byte (usually register number)
 # Returns: -1 on failure, the read byte on success.
+# Read byte data values are cached by default. As we keep reading the
+# same registers over and over again in the detection functions, and
+# SMBus can be slow, caching results in a big performance boost.
 sub i2c_smbus_read_byte_data
 {
-  my ($file, $command) = @_;
+  my ($file, $command, $nocache) = @_;
   my @data;
+  if (!$nocache && exists $i2c_byte_cache[$command]) {
+    return $i2c_byte_cache[$command];
+  }
   i2c_smbus_access $file, SMBUS_READ, $command, SMBUS_BYTE_DATA, \@data
          or return -1;
-  return $data[0];
+  return ($i2c_byte_cache[$command] = $data[0]);
 }
 
@@ -3633 +3644 @@
   my $conf = i2c_smbus_read_byte_data($file, 0x01);
 
-  my $hyst = i2c_smbus_read_byte_data($file, 0x02);
+  my $hyst = i2c_smbus_read_byte_data($file, 0x02, NO_CACHE);
   my $maxreg = $chip == 1 ? 0x0f : 0x07;
   for $i (0x04 .. $maxreg) {
-    return if i2c_smbus_read_byte_data($file, $i) != $hyst;
-  }
-
-  my $os = i2c_smbus_read_byte_data($file, 0x03);
+    return if i2c_smbus_read_byte_data($file, $i, NO_CACHE) != $hyst;
+  }
+
+  my $os = i2c_smbus_read_byte_data($file, 0x03, NO_CACHE);
   for $i (0x04 .. $maxreg) {
-    return if i2c_smbus_read_byte_data($file, $i) != $os;
+    return if i2c_smbus_read_byte_data($file, $i, NO_CACHE) != $os;
   }
 
@@ -3697 +3708 @@
   my $os = i2c_smbus_read_byte_data($file, 0x03);
 
-  my $low = i2c_smbus_read_byte_data($file, 0x04);
-  return if i2c_smbus_read_byte_data($file, 0x06) != $low;
-  return if i2c_smbus_read_byte_data($file, 0x07) != $low;
-
-  my $high = i2c_smbus_read_byte_data($file, 0x05);
-  return if i2c_smbus_read_byte_data($file, 0x06) != $high;
-  return if i2c_smbus_read_byte_data($file, 0x07) != $high;
+  my $low = i2c_smbus_read_byte_data($file, 0x04, NO_CACHE);
+  return if i2c_smbus_read_byte_data($file, 0x06, NO_CACHE) != $low;
+  return if i2c_smbus_read_byte_data($file, 0x07, NO_CACHE) != $low;
+
+  my $high = i2c_smbus_read_byte_data($file, 0x05, NO_CACHE);
+  return if i2c_smbus_read_byte_data($file, 0x06, NO_CACHE) != $high;
+  return if i2c_smbus_read_byte_data($file, 0x07, NO_CACHE) != $high;
 
   for ($i = 8; $i <= 248; $i += 40) {
@@ -4054 +4065 @@
 {
   my ($file, $addr) = @_;
-  my $mid = i2c_smbus_read_byte_data($file, 0xfe);
-  my $cid = i2c_smbus_read_byte_data($file, 0xff);
-  my $conf = i2c_smbus_read_byte_data($file, 0x03);
+  my $mid = i2c_smbus_read_byte_data($file, 0xfe, NO_CACHE);
+  my $cid = i2c_smbus_read_byte_data($file, 0xff, NO_CACHE);
+  my $conf = i2c_smbus_read_byte_data($file, 0x03, NO_CACHE);
 
   return if $mid != 0x4d;     # Maxim
@@ -4063 +4074 @@
   return if $cid != 0x4d;     # No register, returns previous value
 
-  my $rate = i2c_smbus_read_byte_data($file, 0x04);
+  my $rate = i2c_smbus_read_byte_data($file, 0x04, NO_CACHE);
   return if $rate > 0x09;
 
-  $cid = i2c_smbus_read_byte_data($file, 0xff);
-  $conf = i2c_smbus_read_byte_data($file, 0x03);
+  $cid = i2c_smbus_read_byte_data($file, 0xff, NO_CACHE);
+  $conf = i2c_smbus_read_byte_data($file, 0x03, NO_CACHE);
   return if ($conf & 0x0f) != $rate; # No low nibble,
                                      # returns previous low nibble