perf: Disallow sparse AUX allocations for non-SG PMUs in overwrite mode
authorAlexander Shishkin <alexander.shishkin@linux.intel.com>
Fri, 22 May 2015 15:30:20 +0000 (18:30 +0300)
committerIngo Molnar <mingo@kernel.org>
Wed, 27 May 2015 07:16:20 +0000 (09:16 +0200)
commitaa319bcd366349c6f72fcd331da89d3d06090651
tree758ff1f596b92f1d424939fc09c72ae4f1a6ed5f
parentcc1790cf541553263bda024295d7600c7cd7c45d
perf: Disallow sparse AUX allocations for non-SG PMUs in overwrite mode

PMUs that don't support hardware scatter tables require big contiguous
chunks of memory and a PMI to switch between them. However, in overwrite
using a PMI for this purpose adds extra overhead that the users would
like to avoid. Thus, in overwrite mode for such PMUs we can only allow
one contiguous chunk for the entire requested buffer.

This patch changes the behavior accordingly, so that if the buddy allocator
fails to come up with a single high-order chunk for the entire requested
buffer, the allocation will fail.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@infradead.org
Cc: adrian.hunter@intel.com
Cc: hpa@zytor.com
Link: http://lkml.kernel.org/r/1432308626-18845-2-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
kernel/events/ring_buffer.c