diff --git a/searchcore/src/vespa/searchcore/proton/server/bootstrapconfigmanager.cpp b/searchcore/src/vespa/searchcore/proton/server/bootstrapconfigmanager.cpp
index a37aa462140..0239d0d4937 100644
--- a/searchcore/src/vespa/searchcore/proton/server/bootstrapconfigmanager.cpp
+++ b/searchcore/src/vespa/searchcore/proton/server/bootstrapconfigmanager.cpp
@@ -86,6 +86,7 @@ BootstrapConfigManager::update(const ConfigSnapshot & snapshot)
         tune._index._indexing._read.setFromConfig<ProtonConfig::Indexing::Read>(conf.indexing.read.io);
         tune._attr._write.setFromConfig<ProtonConfig::Attribute::Write>(conf.attribute.write.io);
         tune._index._search._read.setFromConfig<ProtonConfig::Search, ProtonConfig::Search::Mmap>(conf.search.io, conf.search.mmap);
+        tune._index._search.set_force_memory_map_posting_list(conf.index.cache.postinglist.maxbytes == -1);
         tune._summary._write.setFromConfig<ProtonConfig::Summary::Write>(conf.summary.write.io);
         tune._summary._seqRead.setFromConfig<ProtonConfig::Summary::Read>(conf.summary.read.io);
         tune._summary._randRead.setFromConfig<ProtonConfig::Summary::Read, ProtonConfig::Summary::Read::Mmap>(conf.summary.read.io, conf.summary.read.mmap);
diff --git a/searchcore/src/vespa/searchcore/proton/server/proton.cpp b/searchcore/src/vespa/searchcore/proton/server/proton.cpp
index 7a70baf9eaa..b62236c6312 100644
--- a/searchcore/src/vespa/searchcore/proton/server/proton.cpp
+++ b/searchcore/src/vespa/searchcore/proton/server/proton.cpp
@@ -166,11 +166,11 @@ void ensureWritableDir(const std::string &dirName) {
 std::shared_ptr<IPostingListCache>
 make_posting_list_cache(const ProtonConfig& cfg)
 {
-    if (cfg.search.io == ProtonConfig::Search::Io::MMAP ||
-        (cfg.index.cache.postinglist.maxbytes == 0 && cfg.index.cache.bitvector.maxbytes == 0)) {
-        return {};
+    int64_t max_bytes = cfg.index.cache.postinglist.maxbytes;
+    if (max_bytes == -1) { // Force memory map posting lists, cf. BootstrapConfigManager::update
+        max_bytes = 0;
     }
-    return std::make_shared<PostingListCache>(cfg.index.cache.postinglist.maxbytes, cfg.index.cache.bitvector.maxbytes);
+    return std::make_shared<PostingListCache>(max_bytes, cfg.index.cache.bitvector.maxbytes);
 }
 
 } // namespace <unnamed>
diff --git a/searchlib/src/vespa/searchlib/common/tunefileinfo.cpp b/searchlib/src/vespa/searchlib/common/tunefileinfo.cpp
index 7c95ef8f349..a588cab0d86 100644
--- a/searchlib/src/vespa/searchlib/common/tunefileinfo.cpp
+++ b/searchlib/src/vespa/searchlib/common/tunefileinfo.cpp
@@ -4,4 +4,14 @@
 
 namespace search {
 
+TuneFileRandRead
+TuneFileRandRead::consider_force_memory_map(bool force_memory_map) const noexcept
+{
+    TuneFileRandRead result = *this;
+    if (force_memory_map) {
+        result.setWantMemoryMap();
+    }
+    return result;
+}
+
 } // namespace search
diff --git a/searchlib/src/vespa/searchlib/common/tunefileinfo.h b/searchlib/src/vespa/searchlib/common/tunefileinfo.h
index f7030f463a4..0f3a2b7812e 100644
--- a/searchlib/src/vespa/searchlib/common/tunefileinfo.h
+++ b/searchlib/src/vespa/searchlib/common/tunefileinfo.h
@@ -20,11 +20,11 @@ class TuneFileSeqRead
 
 public:
     TuneFileSeqRead() noexcept : _tuneControl(NORMAL) { }
-    void setWantDirectIO() { _tuneControl = DIRECTIO; }
-    bool getWantDirectIO() const { return _tuneControl == DIRECTIO; }
+    void setWantDirectIO() noexcept { _tuneControl = DIRECTIO; }
+    bool getWantDirectIO() const noexcept { return _tuneControl == DIRECTIO; }
 
     template <typename Config>
-    void setFromConfig(const enum Config::Io &config) {
+    void setFromConfig(const enum Config::Io &config) noexcept {
         switch (config) {
         case Config::Io::NORMAL:
             _tuneControl = NORMAL;
@@ -38,11 +38,11 @@ class TuneFileSeqRead
         }
     }
 
-    bool operator==(const TuneFileSeqRead &rhs) const {
+    bool operator==(const TuneFileSeqRead &rhs) const noexcept {
         return _tuneControl == rhs._tuneControl;
     }
 
-    bool operator!=(const TuneFileSeqRead &rhs) const {
+    bool operator!=(const TuneFileSeqRead &rhs) const noexcept {
         return _tuneControl != rhs._tuneControl;
     }
 };
@@ -63,12 +63,12 @@ class TuneFileSeqWrite
 
 public:
     TuneFileSeqWrite() noexcept : _tuneControl(NORMAL) { }
-    void setWantDirectIO() { _tuneControl = DIRECTIO; }
-    bool getWantDirectIO() const { return _tuneControl == DIRECTIO; }
-    bool getWantSyncWrites() const { return _tuneControl == OSYNC; }
+    void setWantDirectIO() noexcept { _tuneControl = DIRECTIO; }
+    bool getWantDirectIO() const noexcept { return _tuneControl == DIRECTIO; }
+    bool getWantSyncWrites() const noexcept { return _tuneControl == OSYNC; }
 
     template <typename Config>
-    void setFromConfig(const enum Config::Io &config) {
+    void setFromConfig(const enum Config::Io &config) noexcept {
         switch (config) {
         case Config::Io::NORMAL:
             _tuneControl = NORMAL;
@@ -85,8 +85,8 @@ class TuneFileSeqWrite
         }
     }
 
-    bool operator==(const TuneFileSeqWrite &rhs) const { return _tuneControl == rhs._tuneControl; }
-    bool operator!=(const TuneFileSeqWrite &rhs) const { return _tuneControl != rhs._tuneControl; }
+    bool operator==(const TuneFileSeqWrite &rhs) const noexcept { return _tuneControl == rhs._tuneControl; }
+    bool operator!=(const TuneFileSeqWrite &rhs) const noexcept { return _tuneControl != rhs._tuneControl; }
 };
 
 
@@ -105,27 +105,28 @@ class TuneFileRandRead
           _advise(0)
     { }
 
-    void setAdvise(int advise)        { _advise = advise; }
-    void setWantMemoryMap() { _tuneControl = MMAP; }
-    void setWantDirectIO()  { _tuneControl = DIRECTIO; }
-    void setWantNormal()    { _tuneControl = NORMAL; }
-    bool getWantDirectIO()   const { return _tuneControl == DIRECTIO; }
-    bool getWantMemoryMap()  const { return _tuneControl == MMAP; }
-    int  getMemoryMapFlags() const { return _mmapFlags; }
-    int  getAdvise()         const { return _advise; }
+    void setAdvise(int advise) noexcept { _advise = advise; }
+    void setWantMemoryMap() noexcept { _tuneControl = MMAP; }
+    void setWantDirectIO()  noexcept { _tuneControl = DIRECTIO; }
+    void setWantNormal()    noexcept { _tuneControl = NORMAL; }
+    bool getWantDirectIO()   const noexcept { return _tuneControl == DIRECTIO; }
+    bool getWantMemoryMap()  const noexcept { return _tuneControl == MMAP; }
+    int  getMemoryMapFlags() const noexcept { return _mmapFlags; }
+    int  getAdvise()         const noexcept { return _advise; }
 
     template <typename TuneControlConfig, typename MMapConfig>
-    void setFromConfig(const enum TuneControlConfig::Io & tuneControlConfig, const MMapConfig & mmapFlags);
+    void setFromConfig(const enum TuneControlConfig::Io & tuneControlConfig, const MMapConfig & mmapFlags) noexcept;
     template <typename MMapConfig>
-    void setFromMmapConfig(const MMapConfig & mmapFlags);
+    void setFromMmapConfig(const MMapConfig & mmapFlags) noexcept;
 
-    bool operator==(const TuneFileRandRead &rhs) const {
+    bool operator==(const TuneFileRandRead &rhs) const noexcept {
         return (_tuneControl == rhs._tuneControl) && (_mmapFlags == rhs._mmapFlags);
     }
 
-    bool operator!=(const TuneFileRandRead &rhs) const {
+    bool operator!=(const TuneFileRandRead &rhs) const noexcept {
         return (_tuneControl != rhs._tuneControl) && (_mmapFlags == rhs._mmapFlags);
     }
+    TuneFileRandRead consider_force_memory_map(bool force_memory_map) const noexcept;
 };
 
 
@@ -143,11 +144,11 @@ class TuneFileIndexing
 
     TuneFileIndexing(const TuneFileSeqRead &r, const TuneFileSeqWrite &w) noexcept : _read(r), _write(w) { }
 
-    bool operator==(const TuneFileIndexing &rhs) const {
+    bool operator==(const TuneFileIndexing &rhs) const noexcept {
         return _read == rhs._read && _write == rhs._write;
     }
 
-    bool operator!=(const TuneFileIndexing &rhs) const {
+    bool operator!=(const TuneFileIndexing &rhs) const noexcept {
         return _read != rhs._read || _write != rhs._write;
     }
 };
@@ -160,11 +161,19 @@ class TuneFileSearch
 {
 public:
     TuneFileRandRead _read;
+    bool _force_memory_map_posting_list;
 
-    TuneFileSearch() noexcept : _read() { }
-    TuneFileSearch(const TuneFileRandRead &r) noexcept : _read(r) { }
-    bool operator==(const TuneFileSearch &rhs) const { return _read == rhs._read; }
-    bool operator!=(const TuneFileSearch &rhs) const { return _read != rhs._read; }
+    TuneFileSearch() noexcept : _read(), _force_memory_map_posting_list(false) { }
+    TuneFileSearch(const TuneFileRandRead &r) noexcept : _read(r), _force_memory_map_posting_list(false) { }
+    void set_force_memory_map_posting_list(bool value) noexcept { _force_memory_map_posting_list = value; }
+    TuneFileRandRead get_tune_file_search_posting_list() const noexcept {
+        return _read.consider_force_memory_map(_force_memory_map_posting_list);
+    }
+    bool operator==(const TuneFileSearch &rhs) const noexcept {
+        return _read == rhs._read &&
+               _force_memory_map_posting_list == rhs._force_memory_map_posting_list;
+    }
+    bool operator!=(const TuneFileSearch &rhs) const noexcept { return !operator==(rhs); }
 };
 
 
@@ -180,11 +189,11 @@ class TuneFileIndexManager
 
     TuneFileIndexManager() noexcept : _indexing(), _search() { }
 
-    bool operator==(const TuneFileIndexManager &rhs) const {
+    bool operator==(const TuneFileIndexManager &rhs) const noexcept {
         return _indexing == rhs._indexing && _search == rhs._search;
     }
 
-    bool operator!=(const TuneFileIndexManager &rhs) const {
+    bool operator!=(const TuneFileIndexManager &rhs) const noexcept {
         return _indexing != rhs._indexing || _search != rhs._search;
     }
 };
@@ -200,11 +209,11 @@ class TuneFileAttributes
 
     TuneFileAttributes() noexcept : _write() { }
 
-    bool operator==(const TuneFileAttributes &rhs) const {
+    bool operator==(const TuneFileAttributes &rhs) const noexcept {
         return _write == rhs._write;
     }
 
-    bool operator!=(const TuneFileAttributes &rhs) const {
+    bool operator!=(const TuneFileAttributes &rhs) const noexcept {
         return _write != rhs._write;
     }
 };
@@ -222,13 +231,13 @@ class TuneFileSummary
 
     TuneFileSummary() noexcept : _seqRead(), _write(), _randRead() { }
 
-    bool operator==(const TuneFileSummary &rhs) const {
+    bool operator==(const TuneFileSummary &rhs) const noexcept {
         return _seqRead == rhs._seqRead &&
                  _write == rhs._write &&
               _randRead == rhs._randRead;
     }
 
-    bool operator!=(const TuneFileSummary &rhs) const {
+    bool operator!=(const TuneFileSummary &rhs) const noexcept {
         return _seqRead != rhs._seqRead ||
                  _write != rhs._write ||
               _randRead != rhs._randRead;
@@ -250,13 +259,13 @@ class TuneFileDocumentDB
 
     TuneFileDocumentDB() noexcept : _index(), _attr(), _summary() { }
 
-    bool operator==(const TuneFileDocumentDB &rhs) const {
+    bool operator==(const TuneFileDocumentDB &rhs) const noexcept {
         return _index == rhs._index &&
                 _attr == rhs._attr &&
                 _summary == rhs._summary;
     }
 
-    bool operator!=(const TuneFileDocumentDB &rhs) const {
+    bool operator!=(const TuneFileDocumentDB &rhs) const noexcept {
         return _index != rhs._index ||
                 _attr != rhs._attr ||
                 _summary != rhs._summary;
diff --git a/searchlib/src/vespa/searchlib/common/tunefileinfo.hpp b/searchlib/src/vespa/searchlib/common/tunefileinfo.hpp
index 5e997276bb1..615efac9d1d 100644
--- a/searchlib/src/vespa/searchlib/common/tunefileinfo.hpp
+++ b/searchlib/src/vespa/searchlib/common/tunefileinfo.hpp
@@ -10,7 +10,7 @@ namespace search {
 
 template <typename TuneControlConfig, typename MMapConfig>
 void
-TuneFileRandRead::setFromConfig(const enum TuneControlConfig::Io & tuneControlConfig, const MMapConfig & mmapFlags) {
+TuneFileRandRead::setFromConfig(const enum TuneControlConfig::Io & tuneControlConfig, const MMapConfig & mmapFlags) noexcept {
     switch ( tuneControlConfig) {
         case TuneControlConfig::Io::NORMAL:   _tuneControl = NORMAL; break;
         case TuneControlConfig::Io::DIRECTIO: _tuneControl = DIRECTIO; break;
@@ -22,7 +22,7 @@ TuneFileRandRead::setFromConfig(const enum TuneControlConfig::Io & tuneControlCo
 
 template <typename MMapConfig>
 void
-TuneFileRandRead::setFromMmapConfig(const MMapConfig & mmapFlags) {
+TuneFileRandRead::setFromMmapConfig(const MMapConfig & mmapFlags) noexcept {
     for (size_t i(0), m(mmapFlags.options.size()); i < m; i++) {
 #ifdef __linux__
         switch (mmapFlags.options[i]) {
diff --git a/searchlib/src/vespa/searchlib/diskindex/field_index.cpp b/searchlib/src/vespa/searchlib/diskindex/field_index.cpp
index 1fe90d1131b..8606227cf0f 100644
--- a/searchlib/src/vespa/searchlib/diskindex/field_index.cpp
+++ b/searchlib/src/vespa/searchlib/diskindex/field_index.cpp
@@ -138,21 +138,15 @@ FieldIndex::open(const std::string& field_dir, const TuneFileSearch& tune_file_s
             LOG(warning, "Could not detect format for posocc file read %s", postingName.c_str());
         }
     }
-    pFile.reset(dynamicK
-                ? new DiskPostingFileDynamicKReal()
-                : new DiskPostingFileReal());
-    if (!pFile->open(postingName, tune_file_search._read)) {
+    pFile = dynamicK ? std::make_shared<DiskPostingFileDynamicKReal>() : std::make_shared<DiskPostingFileReal>();
+    auto tune_file_search_posting_list = tune_file_search.get_tune_file_search_posting_list();
+    if (!pFile->open(postingName, tune_file_search_posting_list)) {
         LOG(warning, "Could not open posting list file '%s'", postingName.c_str());
         return false;
     }
 
     bDict = std::make_shared<BitVectorDictionary>();
-    // memory map bitvectors unless bitvector cache is enabled
-    auto maybe_force_mmap = tune_file_search._read;
-    if (!_bitvector_cache_enabled) {
-        maybe_force_mmap.setWantMemoryMap();
-    }
-    if (!bDict->open(field_dir, maybe_force_mmap, BitVectorKeyScope::PERFIELD_WORDS)) {
+    if (!bDict->open(field_dir, tune_file_search._read, BitVectorKeyScope::PERFIELD_WORDS)) {
         LOG(warning, "Could not open bit vector dictionary in '%s'", field_dir.c_str());
         return false;
     }