x86/mpx: Trace the attempts to find bounds tables
There are two different events being traced here. They are
doing similar things so share a trace "EVENT_CLASS" and are
presented together.
1. Trace when MPX is zapping pages "mpx_unmap_zap":
When MPX can not free an entire bounds table, it will
instead try to zap unused parts of a bounds table to free
the backing memory. This decreases RSS (resident set
size) without decreasing the virtual space allocated
for bounds tables.
2. Trace attempts to find bounds tables "mpx_unmap_search":
This event traces any time we go looking to unmap a
bounds table for a given virtual address range. This is
useful to ensure that the kernel actually "tried" to free
a bounds table versus times it succeeded in finding one.
It might try and fail if it realized that a table was
shared with an adjacent VMA which is not being unmapped.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183703.B9D2468B@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2 files changed