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author | Ivo Sieben <meltedpianoman@gmail.com> | 2012-09-27 16:02:05 +0400 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-10-23 03:47:51 +0400 |
commit | cee4ad1ed90a0959fc29f9d30a2526e5e9522cfa (patch) | |
tree | 32b33be64fb490a9f7d3c704dea0a44ea3138ca6 /fs/devpts/inode.c | |
parent | daee779718a319ff9f83e1ba3339334ac650bb22 (diff) | |
download | linux-cee4ad1ed90a0959fc29f9d30a2526e5e9522cfa.tar.xz |
tty: prevent unnecessary work queue lock checking on flip buffer copy
When low_latency flag is set the TTY receive flip buffer is copied to the
line discipline directly instead of using a work queue in the background.
Therefor only in case a workqueue is actually used for copying data to the
line discipline we'll have to flush the workqueue.
This prevents unnecessary spin lock/unlock on the workqueue spin lock that
can cause additional scheduling overhead on a PREEMPT_RT system. On a 200
MHz AT91SAM9261 processor setup this fixes about 100us of scheduling
overhead on the TTY read call.
Signed-off-by: Ivo Sieben <meltedpianoman@gmail.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/devpts/inode.c')
0 files changed, 0 insertions, 0 deletions