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| author | Thomas Gleixner <tglx@linutronix.de> | 2019-11-11 23:03:22 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-11-16 11:24:02 +0100 |
| commit | 060aa16fdb7c5078a4159a76e5dc87d6a493af9b (patch) | |
| tree | 63f2ffbc60ce9e1064ca13bc128efeb7c1e7f6c8 /arch/x86/include/asm | |
| parent | 577d5cd7e5851d3832066cd0422475fa7db2ee17 (diff) | |
| download | linux-060aa16fdb7c5078a4159a76e5dc87d6a493af9b.tar.bz2 | |
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>
Diffstat (limited to 'arch/x86/include/asm')
| -rw-r--r-- | arch/x86/include/asm/io_bitmap.h | 1 | ||||
| -rw-r--r-- | arch/x86/include/asm/processor.h | 3 |
2 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/include/asm/io_bitmap.h b/arch/x86/include/asm/io_bitmap.h index 1a12b9ff5e4e..d63bd5afe671 100644 --- a/arch/x86/include/asm/io_bitmap.h +++ b/arch/x86/include/asm/io_bitmap.h @@ -5,6 +5,7 @@ #include <asm/processor.h> struct io_bitmap { + u64 sequence; /* The maximum number of bytes to copy so all zero bits are covered */ unsigned int max; unsigned long bitmap[IO_BITMAP_LONGS]; diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index c949e0e5cbe6..40bb0f7bca3f 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -361,6 +361,9 @@ struct entry_stack_page { * All IO bitmap related data stored in the TSS: */ struct x86_io_bitmap { + /* The sequence number of the last active bitmap. */ + u64 prev_sequence; + /* * Store the dirty size of the last io bitmap offender. The next * one will have to do the cleanup as the switch out to a non io |