diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2010-03-01 09:00:29 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-03-01 09:00:29 -0800 |
| commit | b1bf9368407ae7e89d8a005bb40beb70a41df539 (patch) | |
| tree | 3815c8aab19c6c186736673c624fef5f3faab716 /Documentation | |
| parent | 524df55725217b13d5a232fb5badb5846418ea0e (diff) | |
| parent | 4671a1322052425afa38fcb7980d2fd2bb0fc99b (diff) | |
Merge branch 'for-2.6.34' of git://git.kernel.dk/linux-2.6-block
* 'for-2.6.34' of git://git.kernel.dk/linux-2.6-block: (38 commits)
block: don't access jiffies when initialising io_context
cfq: remove 8 bytes of padding from cfq_rb_root on 64 bit builds
block: fix for "Consolidate phys_segment and hw_segment limits"
cfq-iosched: quantum check tweak
blktrace: perform cleanup after setup error
blkdev: fix merge_bvec_fn return value checks
cfq-iosched: requests "in flight" vs "in driver" clarification
cciss: Fix problem with scatter gather elements in the scsi half of the driver
cciss: eliminate unnecessary pointer use in cciss scsi code
cciss: do not use void pointer for scsi hba data
cciss: factor out scatter gather chain block mapping code
cciss: fix scatter gather chain block dma direction kludge
cciss: simplify scatter gather code
cciss: factor out scatter gather chain block allocation and freeing
cciss: detect bad alignment of scsi commands at build time
cciss: clarify command list padding calculation
cfq-iosched: rethink seeky detection for SSDs
cfq-iosched: rework seeky detection
block: remove padding from io_context on 64bit builds
block: Consolidate phys_segment and hw_segment limits
...
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-block | 14 | ||||
| -rw-r--r-- | Documentation/block/queue-sysfs.txt | 10 |
2 files changed, 19 insertions, 5 deletions
diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block index d2f90334bb9..4873c759d53 100644 --- a/Documentation/ABI/testing/sysfs-block +++ b/Documentation/ABI/testing/sysfs-block @@ -128,3 +128,17 @@ Description: preferred request size for workloads where sustained throughput is desired. If no optimal I/O size is reported this file contains 0. + +What: /sys/block/<disk>/queue/nomerges +Date: January 2010 +Contact: +Description: + Standard I/O elevator operations include attempts to + merge contiguous I/Os. For known random I/O loads these + attempts will always fail and result in extra cycles + being spent in the kernel. This allows one to turn off + this behavior on one of two ways: When set to 1, complex + merge checks are disabled, but the simple one-shot merges + with the previous I/O request are enabled. When set to 2, + all merge tries are disabled. The default value is 0 - + which enables all types of merge tries. diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt index e164403f60e..f65274081c8 100644 --- a/Documentation/block/queue-sysfs.txt +++ b/Documentation/block/queue-sysfs.txt @@ -25,11 +25,11 @@ size allowed by the hardware. nomerges (RW) ------------- -This enables the user to disable the lookup logic involved with IO merging -requests in the block layer. Merging may still occur through a direct -1-hit cache, since that comes for (almost) free. The IO scheduler will not -waste cycles doing tree/hash lookups for merges if nomerges is 1. Defaults -to 0, enabling all merges. +This enables the user to disable the lookup logic involved with IO +merging requests in the block layer. By default (0) all merges are +enabled. When set to 1 only simple one-hit merges will be tried. When +set to 2 no merge algorithms will be tried (including one-hit or more +complex tree/hash lookups). nr_requests (RW) ---------------- |