mirror of
https://github.com/torvalds/linux.git
synced 2024-11-17 01:22:07 +00:00
194ec34184
The function graph tracer replaces the return address with a hook to trace the exit of the function call. This hook will finish by returning to the real location the function should return to. But the current implementation uses a ret to jump to the real return location. This causes a imbalance between calls and ret. That is the original function does a call, the ret goes to the handler and then the handler does a ret without a matching call. Although the function graph tracer itself still breaks the branch predictor by replacing the original ret, by using a second ret and causing an imbalance, it breaks the predictor even more. This patch replaces the ret with a jmp to keep the calls and ret balanced. I tested this on one box and it showed a 1.7% increase in performance. Another box only showed a small 0.3% increase. But no box that I tested this on showed a decrease in performance by making this change. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <20091013203425.042034383@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> |
||
|---|---|---|
| .. | ||
| alpha | ||
| arm | ||
| avr32 | ||
| blackfin | ||
| cris | ||
| frv | ||
| h8300 | ||
| ia64 | ||
| m32r | ||
| m68k | ||
| m68knommu | ||
| microblaze | ||
| mips | ||
| mn10300 | ||
| parisc | ||
| powerpc | ||
| s390 | ||
| score | ||
| sh | ||
| sparc | ||
| um | ||
| x86 | ||
| xtensa | ||
| .gitignore | ||
| Kconfig | ||