Thomas Gleixner 060aa16fdb x86/ioperm: Add bitmap sequence number
Add a globally unique sequence number which is incremented when ioperm() is
changing the I/O bitmap of a task. Store the new sequence number in the
io_bitmap structure and compare it with the sequence number of the I/O
bitmap which was last loaded on a CPU. Only update the bitmap if the
sequence is different.

That should further reduce the overhead of I/O bitmap scheduling when there
are only a few I/O bitmap users on the system.

The 64bit sequence counter is sufficient. A wraparound of the sequence
counter assuming an ioperm() call every nanosecond would require about 584
years of uptime.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2019-11-16 11:24:02 +01:00
..
2019-09-25 17:51:41 -07:00
2019-10-22 09:59:43 -07:00
2019-11-10 13:41:59 -08:00
2019-11-10 13:41:59 -08:00
2019-09-27 13:02:19 -07:00