mem-cache: Accuracy-based rate control for prefetchers

Added a mechanism to control the number of prefetches generated
based in the effectiveness of the prefetches generated so far.

Change-Id: I33af82546f74a5b5ab372c28574b76dd9a1bd46a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18808
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/src/mem/cache/prefetch/Prefetcher.py b/src/mem/cache/prefetch/Prefetcher.py
index bf735264a..c7ddcda1c 100644
--- a/src/mem/cache/prefetch/Prefetcher.py
+++ b/src/mem/cache/prefetch/Prefetcher.py
@@ -129,6 +129,18 @@ class QueuedPrefetcher(BasePrefetcher):
 
     tag_prefetch = Param.Bool(True, "Tag prefetch with PC of generating access")
 
+    # The throttle_control_percentage controls how many of the candidate
+    # addresses generated by the prefetcher will be finally turned into
+    # prefetch requests
+    # - If set to 100, all candidates can be discarded (one request
+    #   will always be allowed to be generated)
+    # - Setting it to 0 will disable the throttle control, so requests are
+    #   created for all candidates
+    # - If set to 60, 40% of candidates will generate a request, and the
+    #   remaining 60% will be generated depending on the current accuracy
+    throttle_control_percentage = Param.Percent(0, "Percentage of requests \
+        that can be throttled depending on the accuracy of the prefetcher.")
+
 class StridePrefetcher(QueuedPrefetcher):
     type = 'StridePrefetcher'
     cxx_class = 'StridePrefetcher'