pm24.git/block, branch v2.6.34-rc1

Driver core: Constify struct sysfs_ops in struct kobj_type

2010-03-08T01:04:49Z

Constify struct sysfs_ops. This is part of the ops structure constification effort started by Arjan van de Ven et al. Benefits of this constification: * prevents modification of data that is shared (referenced) by many other structure instances at runtime * detects/prevents accidental (but not intentional) modification attempts on archs that enforce read-only kernel data at runtime * potentially better optimized code as the compiler can assume that the const data cannot be changed * the compiler/linker move const data into .rodata and therefore exclude them from false sharing Signed-off-by: Emese Revfy Acked-by: David Teigland Acked-by: Matt Domsch Acked-by: Maciej Sosnowski Acked-by: Hans J. Koch Acked-by: Pekka Enberg Acked-by: Jens Axboe Acked-by: Stephen Hemminger Signed-off-by: Greg Kroah-Hartman

block: don't access jiffies when initialising io_context

2010-03-01T09:57:22Z

As the comment says the initial value of last_waited is never used, so there is no need to initialise it with the current jiffies. Jiffies is hot enough without accessing it for no reason. Signed-off-by: Richard Kennedy Signed-off-by: Jens Axboe

cfq: remove 8 bytes of padding from cfq_rb_root on 64 bit builds

2010-03-01T09:50:20Z

Reorder cfq_rb_root to remove 8 bytes of padding on 64 bit builds. Consequently removing 56 bytes from cfq_group and 64 bytes from cfq_data. Signed-off-by: Richard Kennedy Signed-off-by: Jens Axboe

cfq-iosched: quantum check tweak

2010-03-01T08:20:54Z

Currently a queue can only dispatch up to 4 requests if there are other queues. This isn't optimal, device can handle more requests, for example, AHCI can handle 31 requests. I can understand the limit is for fairness, but we could do a tweak: if the queue still has a lot of slice left, sounds we could ignore the limit. Test shows this boost my workload (two thread randread of a SSD) from 78m/s to 100m/s. Thanks for suggestions from Corrado and Vivek for the patch. Signed-off-by: Shaohua Li Signed-off-by: Jens Axboe

cfq-iosched: requests "in flight" vs "in driver" clarification

2010-02-28T18:45:05Z

Counters for requests "in flight" and "in driver" are used asymmetrically in cfq_may_dispatch, and have slightly different meaning. We split the rq_in_flight counter (was sync_flight) to count both sync and async requests, in order to use this one, which is more accurate in some corner cases. The rq_in_driver counter is coalesced, since individual sync/async counts are not used any more. Signed-off-by: Corrado Zoccolo Signed-off-by: Jens Axboe

cfq-iosched: rethink seeky detection for SSDs

2010-02-28T18:41:25Z

CFQ currently applies the same logic of detecting seeky queues and grouping them together for rotational disks as well as SSDs. For SSDs, the time to complete a request doesn't depend on the request location, but only on the size. This patch therefore changes the criterion to group queues by request size in case of SSDs, in order to achieve better fairness. Signed-off-by: Corrado Zoccolo Signed-off-by: Jens Axboe

cfq-iosched: rework seeky detection

2010-02-28T18:41:25Z

Current seeky detection is based on average seek lenght. This is suboptimal, since the average will not distinguish between: * a process doing medium sized seeks * a process doing some sequential requests interleaved with larger seeks and even a medium seek can take lot of time, if the requested sector happens to be behind the disk head in the rotation (50% probability). Therefore, we change the seeky queue detection to work as follows: * each request can be classified as sequential if it is very close to the current head position, i.e. it is likely in the disk cache (disks usually read more data than requested, and put it in cache for subsequent reads). Otherwise, the request is classified as seeky. * an history window of the last 32 requests is kept, storing the classification result. * A queue is marked as seeky if more than 1/8 of the last 32 requests were seeky. This patch fixes a regression reported by Yanmin, on mmap 64k random reads. Reported-by: Yanmin Zhang Signed-off-by: Corrado Zoccolo Signed-off-by: Jens Axboe

block: Consolidate phys_segment and hw_segment limits

2010-02-26T12:58:08Z

Except for SCSI no device drivers distinguish between physical and hardware segment limits. Consolidate the two into a single segment limit. Signed-off-by: Martin K. Petersen Signed-off-by: Jens Axboe

block: Rename blk_queue_max_sectors to blk_queue_max_hw_sectors

2010-02-26T12:58:08Z

The block layer calling convention is blk_queue_. blk_queue_max_sectors predates this practice, leading to some confusion. Rename the function to appropriately reflect that its intended use is to set max_hw_sectors. Also introduce a temporary wrapper for backwards compability. This can be removed after the merge window is closed. Signed-off-by: Martin K. Petersen Signed-off-by: Jens Axboe

block: Add BLK_ prefix to definitions

2010-02-26T12:58:08Z

Add a BLK_ prefix to block layer constants. Signed-off-by: Martin K. Petersen Signed-off-by: Jens Axboe