commit d745c72af8f367b2b1595c36fa922ca1f44388e6
author Mark Salyzyn <salyzyn@google.com> Wed Sep 30 07:40:09 2015 -0700
committer Mark Salyzyn <salyzyn@google.com> Tue Oct 13 13:43:16 2015 -0700
tree 2212796fba83433ec3fd8aac7b55044a6bf53189
parent 33f3a668a81356e7e83c1d1a476f0cb8460e59ca

logd: correct for number of elements in prune

Chatty logs would distort the average log size by elevating the
elements, but not the size. Add statistical collection for the
number of elements that report chatty, and subtract that from
the number of elements to improve the pruning estimate. Pick
minElements as 1% rather than 10% of the total with this more
accurate number of elements, to a minumum of 4.

Bug: 24511000
Change-Id: I3f36558138aa0b2a50e4fac6440c3a8505d95276

logd/LogBuffer.cpp

diff --git a/logd/LogBuffer.cpp b/logd/LogBuffer.cpp
index 1b68386..1de8e64 100644
--- a/logd/LogBuffer.cpp
+++ b/logd/LogBuffer.cpp
@@ -225,8 +225,11 @@
     unsigned long maxSize = log_buffer_size(id);
     if (sizes > maxSize) {
         size_t sizeOver = sizes - ((maxSize * 9) / 10);
-        size_t elements = stats.elements(id);
-        size_t minElements = elements / 10;
+        size_t elements = stats.realElements(id);
+        size_t minElements = elements / 100;
+        if (minElements < minPrune) {
+            minElements = minPrune;
+        }
         unsigned long pruneRows = elements * sizeOver / sizes;
         if (pruneRows < minElements) {
             pruneRows = minElements;

logd/LogBuffer.h

diff --git a/logd/LogBuffer.h b/logd/LogBuffer.h
index 5223b40..7ed92e9 100644
--- a/logd/LogBuffer.h
+++ b/logd/LogBuffer.h
@@ -86,6 +86,7 @@
 
 private:
 
+    static constexpr size_t minPrune = 4;
     static constexpr size_t maxPrune = 256;
 
     void maybePrune(log_id_t id);

logd/LogStatistics.cpp

diff --git a/logd/LogStatistics.cpp b/logd/LogStatistics.cpp
index c3b10ad..fdb2576 100644
--- a/logd/LogStatistics.cpp
+++ b/logd/LogStatistics.cpp
@@ -27,6 +27,7 @@
     log_id_for_each(id) {
         mSizes[id] = 0;
         mElements[id] = 0;
+        mDroppedElements[id] = 0;
         mSizesTotal[id] = 0;
         mElementsTotal[id] = 0;
     }
@@ -93,6 +94,9 @@
     unsigned short size = element->getMsgLen();
     mSizes[log_id] -= size;
     --mElements[log_id];
+    if (element->getDropped()) {
+        --mDroppedElements[log_id];
+    }
 
     if (log_id == LOG_ID_KERNEL) {
         return;
@@ -119,6 +123,7 @@
     log_id_t log_id = element->getLogId();
     unsigned short size = element->getMsgLen();
     mSizes[log_id] -= size;
+    ++mDroppedElements[log_id];
 
     uidTable[log_id].drop(element->getUid(), element);
 

logd/LogStatistics.h

diff --git a/logd/LogStatistics.h b/logd/LogStatistics.h
index 8b90c53..6943820 100644
--- a/logd/LogStatistics.h
+++ b/logd/LogStatistics.h
@@ -374,6 +374,7 @@
 class LogStatistics {
     size_t mSizes[LOG_ID_MAX];
     size_t mElements[LOG_ID_MAX];
+    size_t mDroppedElements[LOG_ID_MAX];
     size_t mSizesTotal[LOG_ID_MAX];
     size_t mElementsTotal[LOG_ID_MAX];
     bool enable;
@@ -404,7 +405,11 @@
     // entry->setDropped(1) must follow this call
     void drop(LogBufferElement *entry);
     // Correct for coalescing two entries referencing dropped content
-    void erase(LogBufferElement *e) { --mElements[e->getLogId()]; }
+    void erase(LogBufferElement *element) {
+        log_id_t log_id = element->getLogId();
+        --mElements[log_id];
+        --mDroppedElements[log_id];
+    }
 
     std::unique_ptr<const UidEntry *[]> sort(size_t len, log_id id) {
         return uidTable[id].sort(len);
@@ -413,6 +418,9 @@
     // fast track current value by id only
     size_t sizes(log_id_t id) const { return mSizes[id]; }
     size_t elements(log_id_t id) const { return mElements[id]; }
+    size_t realElements(log_id_t id) const {
+        return mElements[id] - mDroppedElements[id];
+    }
     size_t sizesTotal(log_id_t id) const { return mSizesTotal[id]; }
     size_t elementsTotal(log_id_t id) const { return mElementsTotal[id]; }