[PATCH] 2.5.8 IDE 35

- Expand configure help options a bit
- Fix xconfig bug
- Decrease queue depth if a command takes too long to complete
- Test master/slave stuff. It works, but one device can heavily starve
   another. This is the simple approach right now, means that one device
   will wait until the other is completely idle before starting any
   commands This is not necessary since we can have queued commands on
   both devices at the same time. TODO.
- Add proc output for oldest command, just for testing.
- pci_dev compile fixes.
- Make sure ide-disk doesn't BUG if TCQ is not used, basically this was
   fixed by off-loading the using_tcq setting to ide-tcq.
- Remove warning about 'queued feature set not supported'
- Abstract ide_tcq_wait_dataphase() into a function

1 files changed, 23 insertions, 3 deletions

diff --git a/drivers/ide/Config.help b/drivers/ide/Config.help
index 942a3b00d346..0f1a67ef1fe9 100644
--- a/drivers/ide/Config.help
+++ b/drivers/ide/Config.help
@@ -753,9 +753,17 @@ CONFIG_BLK_DEV_IDE_TCQ
 
   If you have such a drive, say Y here.
 
-CONFIG_BLK_DEV_IDE_TCQ_DEFAULT
-  Enabled tagged command queueing unconditionally on drives that report
-  support for it.
+CONFIG_BLK_DEV_IDE_TCQ_FULL
+  When a command completes from the drive, the SERVICE bit is checked to
+  see if other queued commands are ready to be started. Doing this
+  immediately after a command completes has a tendency to 'starve' the
+  device hardware queue, since we risk emptying the queue completely
+  before starting any new commands. This shows up during stressing the
+  drive as a /\/\/\/\ queue size balance, where we could instead try and
+  maintain a minimum queue size and get a /---------\ graph instead.
+
+  Saying Y here will attempt to always keep the queue full when possible
+  at the cost of possibly increasing command turn-around latency.
 
   Generally say Y here.
 
@@ -766,6 +774,18 @@ CONFIG_BLK_DEV_IDE_TCQ_DEPTH
   You probably just want the default of 32 here. If you enter an invalid
   number, the default value will be used.
 
+CONFIG_BLK_DEV_IDE_TCQ_DEFAULT
+  Enabled tagged command queueing unconditionally on drives that report
+  support for it. Regardless of the chosen value here, tagging can be
+  controlled at run time:
+
+  echo "using_tcq:32" > /proc/ide/hdX/settings
+
+  where any value between 1-32 selects chosen queue depth and enables
+  TCQ, and 0 disables it.
+
+  Generally say Y here.
+
 CONFIG_BLK_DEV_IT8172
   Say Y here to support the on-board IDE controller on the Integrated
   Technology Express, Inc. ITE8172 SBC.  Vendor page at