[PATCH] update max_sectors documentation

[PATCH] update max_sectors documentation

[Mike Christie]

Hi Jens,

I was looking over Kai's scsi command size email and was going to try
and add it to some block docs and noticed I did not send the update to
the max_sectors biodoc.txt. Sorry about that. Here is the patch against
2.6.16-rc5.

The max_sectors has been split into max_hw_sectors and max_sectors for some
time. A patch to have blk_queue_max_sectors enforce this was sent by
me and it broke IDE. This patch updates the documentation.


--- linux-2.6.16-rc5/Documentation/block/biodoc.txt	2006-02-26 23:09:35.000000000 -0600
+++ linux-2.6.16-rc5.work/Documentation/block/biodoc.txt	2006-03-07 18:10:57.000000000 -0600
@@ -132,8 +132,18 @@ Some new queue property settings:
 		limit. No highmem default.
 
 	blk_queue_max_sectors(q, max_sectors)
-		Maximum size request you can handle in units of 512 byte
-		sectors. 255 default.
+		Sets two variables that limit the size of the request.
+
+		- The request queue's max_sectors, which is a soft size in
+		in units of 512 byte sectors, and could be dynamically varied
+		by the core kernel.
+
+		- The request queue's max_hw_sectors, which is a hard limit
+		and reflects the maximum size request a driver can handle
+		in units of 512 byte sectors.
+
+		The default for both max_sectors and max_hw_sectors is
+		255. The upper limit of max_sectors is 1024.
 
 	blk_queue_max_phys_segments(q, max_segments)
 		Maximum physical segments you can handle in a request. 128

Re: [PATCH] update max_sectors documentation

[Jens Axboe]

On Tue, Mar 07 2006, Mike Christie wrote:
> Hi Jens,
> 
> I was looking over Kai's scsi command size email and was going to try
> and add it to some block docs and noticed I did not send the update to
> the max_sectors biodoc.txt. Sorry about that. Here is the patch against
> 2.6.16-rc5.
> 
> The max_sectors has been split into max_hw_sectors and max_sectors for some
> time. A patch to have blk_queue_max_sectors enforce this was sent by
> me and it broke IDE. This patch updates the documentation.

Thanks Mike, committed.

-- 
Jens Axboe