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| author | Jens Axboe <axboe@fb.com> | 2015-07-16 09:14:26 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-07-17 08:41:53 -0600 |
| commit | 0034af036554c39eefd14d835a8ec3496ac46712 (patch) | |
| tree | 54a9262ca37905600872eb8638d5453a82f59520 /block/blk-settings.c | |
| parent | 2bb4cd5cc472b191a46938becb7dafdd44644329 (diff) | |
| download | lwn-0034af036554c39eefd14d835a8ec3496ac46712.tar.gz lwn-0034af036554c39eefd14d835a8ec3496ac46712.zip | |
block: make /sys/block/<dev>/queue/discard_max_bytes writeable
Lots of devices support huge discard sizes these days. Depending
on how the device handles them internally, huge discards can
introduce massive latencies (hundreds of msec) on the device side.
We have a sysfs file, discard_max_bytes, that advertises the max
hardware supported discard size. Make this writeable, and split
the settings into a soft and hard limit. This can be set from
'discard_granularity' and up to the hardware limit.
Add a new sysfs file, 'discard_max_hw_bytes', that shows the hw
set limit.
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-settings.c')
| -rw-r--r-- | block/blk-settings.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c index 12600bfffca9..b38d8d723276 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -116,6 +116,7 @@ void blk_set_default_limits(struct queue_limits *lim) lim->chunk_sectors = 0; lim->max_write_same_sectors = 0; lim->max_discard_sectors = 0; + lim->max_hw_discard_sectors = 0; lim->discard_granularity = 0; lim->discard_alignment = 0; lim->discard_misaligned = 0; @@ -303,6 +304,7 @@ EXPORT_SYMBOL(blk_queue_chunk_sectors); void blk_queue_max_discard_sectors(struct request_queue *q, unsigned int max_discard_sectors) { + q->limits.max_hw_discard_sectors = max_discard_sectors; q->limits.max_discard_sectors = max_discard_sectors; } EXPORT_SYMBOL(blk_queue_max_discard_sectors); @@ -641,6 +643,8 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, t->max_discard_sectors = min_not_zero(t->max_discard_sectors, b->max_discard_sectors); + t->max_hw_discard_sectors = min_not_zero(t->max_hw_discard_sectors, + b->max_hw_discard_sectors); t->discard_granularity = max(t->discard_granularity, b->discard_granularity); t->discard_alignment = lcm_not_zero(t->discard_alignment, alignment) % |