perf/x86/intel/pt: Untangle pt_buffer_reset_markers()
Currently, pt_buffer_reset_markers() is a difficult to read knot of arithmetics with a redundant check for multiple-entry TOPA capability, a commented out wakeup marker placement and a logical error wrt to stop marker placement. The latter happens when write head is not page aligned and results in stop marker being placed one page earlier than it actually should. All these problems only affect PT implementations that support multiple-entry TOPA tables (read: proper scatter-gather). For single-entry TOPA implementations, there is no functional impact. This patch deals with all of the above. Tested on both single-entry and multiple-entry TOPA PT implementations. 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/1432308626-18845-4-git-send-email-alexander.shishkin@linux.intel.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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